Vitt, Dale & Buck, William. (1992). Key to the moss genera of North America north of Mexico. Contribution to the University of Michigan Herbarium. 18. 43-72.
This key works with Mosses of Eastern North America, Howard A. Crum and Lewis E. Anderson, 1982, Columbia University Press
1 - Gametophytes seemingly absent (consisting only of protonemata); sporophytes of asymmetric capsules and papillose setae -- Buxbaumia
1 - Gametophytes present (with obvious leaves); sporophytes various -- 2
2 - Leaf cells arranged in a network of narrow, green cells alternating with large hyaline cells; branches usually in clusters -- Sphagnum
2 - Leaf cells of one kind (green), or if of two kinds, branches never in clusters -- 3
3 - Leaves attached in two rows on opposite sides of the stem (distichous) -- 4
3 - Leaves attached all around the stem (foliate stems sometimes complanate) -- 7
4 - Leaves appearing split at the base, consisting of two vaginant laminae which clasp the stem and base of the leaf above (equitant) -- Fissidens
4 - Leaves with expanded bases, not clasping leaf above -- 5
5 - Leaves ecostate; protonemata luminous -- Schistostega
5 - Leaves unicostate; protonemata not luminous -- 6
6 - All leaves with a rough (papillose), linear subula -- Distichium
6 - Vegetative leaves with a smooth mucro; perichaetial leaves with a smooth subula -- Bryoxiphium
7 - Leaves with lamellae or filaments on the adaxial (upper) surface of the costa (excluding propagula) -- 8
7 - Leaves without lamellae or filaments on the adaxial surface of the costa (but propagula sometimes present) -- 23
8 - Leaves with filaments on the adaxial surface of the costa -- 9
8 - Leaves with lamellae on the adaxial surface of the costa -- 10
9 - Leaf margins broadly inrolled (and mostly obscuring the filaments) -- Aloina
9 - Leaf margins reflexed to revolute -- Crossidium
10 - Leaves bordered with elongate cells -- Atrichum
10 - Leaves without elongate, marginal cells -- 11
11 - Leaves ciliate at upper part of hyaline sheath -- Bartramiopsis
11 - Leaves eciliate -- 12
12 - Upper leaf margins bistratose with paired, multicellular teeth; leaf apices with slender, smooth, caducous awns; restricted to the arctic -- Lyellia
12 - Upper leaf margins unistratose with single teeth or entire; leaf apices muticous or with serrate awns -- 13
13 - Lamellae 2-4; leaves hyaline awned; plants small, less than 5 mm; peristome none or rudimentary and fragile -- Pterygoneurum
13 - Lamellae 4-50; leaves mostly not awned; plants mostly larger; peristome of 32 or 64 persistent teeth -- 14
14 - Lamellae distinctly wavy -- 15
14 - Lamellae straight -- 16
15 - Upper leaf margins with border of hyaline, short- rhombic cells -- Psilopilum
15 - Upper leaf margins not bordered -- Oligotrichum
16 - Leaf laminae with teeth on abaxial (back) surface; calyptrae naked or with a few hairs -- Oligotrichum
16 - Leaf laminae smooth at back; calyptrae densely hairy -- 17
17 - Plants with capsules -- 18
17 - Plants without capsules -- 20
18 - Capsules (2-)4(-6)-angled -- Polytrichum
18 - Capsules cylindric -- 19
19 - Capsules without stomates; lumina of apical cells of lamellae not pyriform -- Pogonatum
19 - Capsules with stomates; lumina of apical cells of lamellae pyriform -- Polytrichastrum
20 - Apical cells of lamellae smooth or with faint cuticular ridges -- 21
20 - Apical cells of lamellae papillose -- 22
21 - Plants small, less than 6 mm high; leaves never awned -- Pogonatum
21 - Plants larger; leaves with or without awns -- Polytrichum
22 - Apical cells of lamellae rounded, quadrate or oblate -- Pogonatum
22 - Apical cells elliptic-pyriform -- Polytrichastrum
23 - Leaves deeply lobed with lobes linear-terete -- Takakia
23 - Leaves never lobed, flattened (although sometimes concave with margins inrolled or recurved) -- 24
24 - Leaves without a costa or costa short and double, double, or single with 2-3 lateral spurs -- 25
24 - Leaves with a single costa to at least midleaf -- 114
25 - Although appearing none, costa single and occupying entire leaf area, thus leaf appearing multistratose -- 26
25 - Costa truly none or double; lamina always unistratose -- 27
26 - Leaves ligulate; green cells (chlorocysts) three- sided in section -- Octoblepharum
26 - Leaves lanceolate; green cells four-sided in section -- Leucobryum
27 - Upper leaf cells papillose or prorulose -- 28
27 - Upper leaf cells smooth (rarely with minute cuticular roughenings) -- 46
28 - Leaf apices hyaline -- 29
28 - Leaf apices concolorous -- 30
29 - Leaf cells with a single, unbranched papillae (on each surface); capsules exserted, ribbed; perichaetial leaves entire; restricted to western North America -- Pseudobraunia
29 - Leaf cells with 1-2 forked papilla (on each surface); capsules immersed, smooth; perichaetial leaves ciliate; widespread -- Hedwigia
30 - Leaf cells pluripapillose -- 31
30 - Leaf cells unipapillose or prorulose -- 33
31 - Papillae arranged in rows over the lumina; leaf cells more than 5:1 -- Taxithelium
31 - Papillae randomly arranged over lumina; leaf cells less than 4:1 -- 32
32 - Leaves obtuse; stems complanate-foliate -- Erpodium
32 - Leaves short-acuminate; stems symmetrically foliate -- Braunia
33 - Plants 2-3 pinnate, each year forming a flattened frond, the fronds arranged in a stair-step ascending pattern -- Hylocomium
33 - Plants simple or 1-pinnate, not forming ascending fronds -- 34
34 - Leaves plicate -- 35
34 - Leaves not plicate -- 36
35 - Costa double and extending to above midleaf; leaves spreading to squarrose -- Rhytidiadelphus
35 - Costa short and double; leaves falcate-secund -- Ctenidium
36 - Plants reddish-black, occurring tightly attached to rocks -- Andreaea
36 - Plants greenish, occurring on various substrates -- 37
37 - Plants minute, less than 2 mm, acrocarpous -- Ephemerum
37 - Plants large, more than 1 cm, pleurocarpous -- 38
38 - Costa strong and double, extending to near leaf apex -- Callicostella
38 - Costa short and double, ending below midleaf -- 39
39 - Alar cells numerous, oblate to rounded, strongly differentiated and extending up the margins; restricted to Pacific Northwest -- Pterogonium
39 - Alar cells few, mostly quadrate, scarcely extending up the margins; widespread -- 40
40 - Cells at midleaf more than 5:1 -- 41
40 - Cells at midleaf less than 5:1 -- 43
41 - Apical leaf cells much shorter than those at midleaf -- Taxiphyllum
41 - Apical leaf cells scarcely differentiated -- 42
42 - Leaves slenderly acuminate; prorulose at both upper and lower ends of cells -- Chrysohypnum
42 - Leaves acute; prorulose only at upper ends of cells -- Leptohymenium
43 - Stem and branch leaves differentiated -- Heterocladium
43 - Stem and branch leaves similar -- 44
44 - Leaves broadly ovate, concave, obtuse to obtuse- apiculate -- Myurella
44 - Leaves lanceolate to ovate-lanceolate, acute to acuminate -- 45
45 - Leaves acute, serrulate only above; propagula often in leaf axils; northern in distribution -- Pterigynandrum
45 - Leaves acuminate, serrulate throughout; propagula absent; eastern US in distribution -- Schwetschkeopsis
46 - Leaves ending in a hyaline awn -- 47
46 - Leaves concolorous at apex -- 48
47 - Leaf cells 2:1 or less, oblate-hexagonal throughout; eperistomate -- Erpodium
47 - Leaf cells more than 3:1, upper cells short rhomboidal, basal cells quadrate; peristomate -- Venturiella
48 - Plants aquatic, occurring submerged at least part of the year; leaves keeled or flat -- Fontinalis
48 - Plants sometimes in wet habitats but never occurring submerged; leaves various but never keeled -- 49
49 - Plants acrocarpous, usually less than 4 cm -- 50
49 - Plants pleurocarpous, mostly larger -- 53
50 - Plants occurring on rock -- 51
50 - Plants occurring on bare soil -- 52
51 - Plants reddish-black; capsules valvate -- Andreaea
51 - Plants greenish-brown; capsules with four peristome teeth -- Tetrodontium
52 - Protonemata abundant; capsules ovoid, apiculate; calyptrae campanulate-mitrate, deciduous -- Ephemerum
52 - Protonemata sparse; capsules globose; calyptrae very small, persistent -- Micromitrium
53 - Costa single with one or sometimes two supplementary costae on each side -- Antitrichia
53 - Costa always double, or if single very short and without supplementary costae -- 54
54 - Costa long and double, extending to or beyond midleaf -- 55
54 - Costa short and double, usually ending just above leaf base -- 59
55 - Stems with numerous paraphyllia -- 56
55 - Stems lacking paraphyllia -- 57
56 - Stem leaves plicate, decurrent -- Hylocomiastrum
56 - Stem leaves not plicate or decurrent -- Loeskeobryum
57 - Leaf cells thin-walled, lax, abruptly bordered by elongate cells -- Cyclodictyon
57 - Leaf cells firm-walled, not or only gradually bordered -- 58
58 - Plants forming mats; leaves falcate-secund at least at branch apices; exostome teeth striate, furrowed -- Trachyxiphium
58 - Plants tufted; leaves somewhat contorted when dry but not falcate; exostome teeth papillose, not furrowed -- Lepidopilum
59 - Leaves obtuse; plants small, rare, restricted to the mountains of southeastern US -- 60
59 - Leaves acute to acuminate, at least apiculate; plants mostly larger, widespread -- 61
60 - Leaves asymmetric with a basal lobe -- Homaliadelphus
60 - Leaves symmetric without lobe -- Bryocrumia
61 - Leaf cells lax, hexagonal -- 62
61 - Leaf cells firm- to thick-walled, rounded to linear -- 63
62 - Lateral and dorsal leaves differentiated in areolation; stems pinnately branched -- Vesicularia
62 - Lateral and dorsal leaves with similar areolation; stems irregularly branched -- Hookeria
63 - Leaves slenderly long-decurrent -- Plagiothecium
63 - Leaves not at all decurrent to broadly auriculate -- 64
64 - Plants slender, thread-like; leaves mostly less than 1 mm long -- 65
64 - Plants larger; leaves more than 1 mm long -- 67
65 - Branch leaves more than 0 - 5 mm long -- Homomallium
65 - Branch leaves less than 0 - 5 mm long -- 66
66 - Costa short and single; leaf cells rounded-elliptic -- Pseudoleskeella
66 - Costa none or very short and double; leaf cells rhombic -- Platydictya
67 - Leaves falcate-secund -- 68
67 - Leaves straight -- 84
68 - Upper leaf cells oblong-rhombic, about 3:1 -- 69
68 - Leaf cells more or less linear, more than 6:1 -- 70
69 - Alar cells numerous, oblate, extending up the margins in many rows -- Leucodon
69 - Alar cells few, oblong-quadrate, in 1-2 rows along the insertion -- Sematophyllum
70 - Plants regularly and closely pinnate, feather-like; fronds flat, erect to ascending, oblong-triangular -- Ptilium
70 - Plants irregularly pinnate to unbranched, not feather-like; stems prostrate to loosely ascending -- 71
71 - Mature branches erect and producing abundant and conspicuous propagula in their upper leaf axils -- Platygyrium
71 - Branches not producing propagula in leaf axils -- 72
72 - Branches curved-secund when dry, erect when moist; alar cells small and quadrate -- Pylaisiella
72 - Branches little altered when dry; alar cells various -- 73
73 - Alar cells when differentiated quadrate, sometimes enlarged but not at all inflated -- 74
73 - Alar cells quadrate to oblong, inflated -- 79
74 - Stems with paraphyllia -- Rhytidiopsis
74 - Stems without paraphyllia -- 75
75 - Plants very large (stem leaves 3.5-5.0 mm), stems ascending to erect; leaves plicate -- Rhytidiadelphus
75 - Plants smaller (stem leaves less than 3.5 mm), stems prostrate to ascending; leaves various -- 76
76 - Alar cells none or very few; pale propagula often clustered in leaf axils -- Isopterygiopsis
76 - Alar cells distinctly differentiated -- 77
77 - Plants occurring on wet rocks in mountain streams -- Hygrohypnum
77 - Plants in various habitats but not as above -- 78
78 - Costa to about 1/3 the leaf length with the two forks not meeting at the base; plants of Alaska and Yukon -- Gollania
78 - Costa mostly shorter, the forks joining at the base; plants widespread -- Hypnum
79 - Plants occurring in calcareous fens or marl pools, dark reddish-brown; leaves obtuse -- Scorpidium
79 - Plants occurring in other habitats, golden to green; leaves acute to acuminate -- 80
80 - Plants occurring on wet rocks in mountain streams -- Hygrohypnum
80 - Plants in various habitats but not as above -- 81
81 - Alar cells thick-walled, inflated in several rows; leaf margins strongly serrate -- Heterophyllium
81 - Alar cells inflated in 1(-2) rows, or if more, thin- walled; leaf margins entire to serrulate -- 82
82 - Stems surrounded by enlarged, thin-walled, hyaline cortical cells (hyalodermis); alar cells in large, subdecurrent areas -- Hypnum
82 - Stems surrounded by small, thick-walled, concolorous cells; alar cells in 1(-2) rows -- 83
83 - Plants very shiny; leaves 0.8-1.4 mm long, densely serrulate above; capsules inclined, asymmetric -- Brotherella
83 - Plants slightly shiny; leaves 0.5-1.1 mm long, distantly serrulate above; capsule erect, symmetric -- Pylaisiadelpha
84 - Stem leaves abruptly contracted to long setaceous point -- 85
84 - Stem leaves acute, acuminate or apiculate -- 86
85 - Leaf apices hyaline; alar cells scarcely differentiated -- Iwatsukiella
85 - Leaf apices yellow; alar cells inflated and hyaline -- Wijkia
86 - Leaves squarrose-recurved when dry, with channeled apices -- 87
86 - Leaves erect to spreading, or if squarrose only when moist, the apices mostly not channeled -- 88
87 - Stem leaves greater than 2-5 mm long; alar cells oblong, somewhat inflated, intramarginal -- Rhytidiadelphus
87 - Stem leaves less than 2-5 mm long; alar cells subquadrate, not at all inflated, marginal -- Campylium
88 - Plants occurring on wet rocks in mountain streams; leaves ovate, concave -- Hygrohypnum
88 - Plants in other habitats but not as above; leaves various -- 89
89 - Stems complanate-foliate -- 90
89 - Stems symmetrically foliate -- 96
90 - Alar cells numerous and quadrate; capsules erect -- Entodon
90 - Alar cells few, variously shaped; capsules usually inclined -- 91
91 - Plants occurring on vertical substrates, tree trunks or rocks -- Neckera
91 - Plants occurring on horizontal substrates, rarely the extreme bases of trees -- 92
92 - Leaf margins serrulate throughout -- 93
92 - Leaf margins entire or serrulate only in upper half -- 94
93 - Apical leaf cells shorter than those at midleaf -- Taxiphyllum
93 - Apical leaf cells undifferentiated -- Herzogiella
94 - Rhizoids arising from leaf axils, papillose; leaf margins more or less entire -- Isopterygiopsis
94 - Rhizoids arising from below leaf insertion, smooth; leaf margins serrulate above -- 95
95 - Pseudoparaphyllia filamentous; annuli not differentiated; plants mostly monoicous -- Isopterygium
95 - Pseudoparaphyllia absent; annuli differentiated; plants mostly dioicous -- Pseudotaxiphyllum
96 - Alar cells inflated -- 97
96 - Alar cells rectangular to quadrate, not inflated -- 101
97 - Plants erect; stems with hyalodermis; alar cells hyaline and in auricles -- Calliergonella
97 - Plants prostrate; stems without hyalodermis; alar cells yellowish, not in auricles -- 98
98 - Alar cells uniform, without an enlarged basal row; stem apices flattened -- Callicladium
98 - Alar cells with an enlarged basal row; stem apices not flattened -- 99
99 - Alar cells rounded to the insertion; exostome teeth furrowed -- Acroporium
99 - Alar cells not rounded to insertion; exostome teeth not furrowed -- 100
100 - Exostome teeth striate; endostome with evident basal membrane and segments; eastern North America -- Sematophyllum
100 - Exostome teeth smooth or faintly papillose; endostome fugaceous, appearing absent; restricted to central Florida in oak scrub -- Donnellia
101 - Plants with numerous (more than 50), quadrate alar cells, extending up the margins by more than 12 rows -- 102
101 - Plants with fewer (less than 25), quadrate to rectangular alar cells, extending up the margins in less than 8 rows -- 107
102 - Stems with numerous paraphyllia -- Alsia
102 - Stems lacking paraphyllia -- 103
103 - Leaves less than 0.8 mm long; cells with obscure cuticular roughenings; western montane -- Leptopterigynandrum
103 - Leaves more than 1 mm long; cells smooth -- 104
104 - Alar cells extending up the margins for less than 1/6 the leaf length -- 105
104 - Alar cells extending up the margins for more than 1/3 the leaf length -- 106
105 - Leaves acuminate, somewhat decurrent; endostome with cilia; plants restricted to coastal western North America, California to British Columbia -- Tripterocladium
105 - Leaves mostly obtuse to acute, rarely acuminate, never decurrent; endostome lacking cilia; plants widespread but not in coastal western North America -- Entodon
106 - Secondary stems freely subpinnately branched -- Forsstroemia
106 - Secondary stems simple or with few branches -- Leucodon
107 - Plants epiphytic with creeping primary stems and erect secondary stems -- 108
107 - Plants terrestrial or rarely on bases of trees, primary and secondary stems not differentiated -- 109
108 - Secondary stems unbranched; leaves spreading with squarrose tips; propagula common -- Jaegerina
108 - Secondary stems irregularly branched; leaves erect; propagula absent -- Neomacounia
109 - Stems with hyalodermis; leaf margins serrulate to base -- Herzogiella
109 - Stems without hyalodermis; leaf margins entire or serrulate above -- 110
110 - Leaves plicate -- Orthothecium
110 - Leaves not plicate -- 111
111 - Leaf apices obtuse-apiculate -- 112
111 - Leaf apices acuminate -- 113
112 - Plants occurring in fens; stems green, sparsely branched -- Pseudocalliergon
112 - Plants widespread in acidic habitats of the boreal forest; stems reddish-orange, pinnately branched -- Pleurozium
113 - Leaf cells porose throughout; pseudoparaphyllia absent or foliose; plants in boreal, arctic and alpine habitats -- Orthothecium
113 - Leaf cells not porose except at insertion; pseudoparaphyllia filamentous; plants of coastal eastern North America inland to the Midwest -- Isopterygium
114 - Plants erect, dendroid or frondose from a nonbranched stipe -- 115
114 - Plants prostrate to erect, simple to pinnately branched -- 121
115 - Leaves bordered by elongate cells -- 116
115 - Leaves not bordered -- 117
116 - Plants with two kinds of leaves, the larger ones with costa ending well below apex, the smaller ones (amphigastria) with excurrent costa -- Hypopterygium
116 - Plants with leaves all of one kind, the costa subpercurrent -- Leucolepis
117 - Stems with paraphyllia or filamentous, paraphyllia-like structures -- 118
117 - Stems without paraphyllia -- 120
118 - Plants epiphytic; stems pinnately frondose, curled when dry, spreading when moist -- Dendroalsia
118 - Plants terrestrial (rarely on tree bases); stems dendroid, little altered when dry -- 119
119 - Branch leaves long-decurrent, the decurrencies of inflated, hyaline cells; stems with lamellae; stem leaves with entire margins -- Pleuroziopsis
119 - Branch leaves cordate to auriculate, the auricles not inflated; stems with paraphyllia; stem leaves with serrate margins -- Climacium
120 - Apical cells of branch leaves rhombic; costa of branch leaves strong, not tapering toward apex -- Thamnobryum
120 - Apical cells of branch leaves long-hexagonal; costa of branch leaves slender, tapering toward apex -- Porotrichum
121 - Plants blackish, tightly attached to rocks in arctic and montane areas; capsules valvate -- 122
121 - Plants greenish to blackish, on various substrates; capsules cleistocarpous or operculate, never valvate -- 123
122 - Plants occurring on calcareous rocks; capsules not hygroscopic, turbinate, obtuse-conic -- Andreaeobryum
122 - Plants occurring on acidic rocks; capsules hygroscopic, when moist elliptic, tapering to a point -- Andreaea
123 - Leaves strongly squarrose-recurved wet or dry; plants occurring in fens -- Paludella
123 - Leaves erect to squarrose; plants occurring in various habitats -- 124
124 - Stems with paraphyllia -- 125
124 - Stems lacking paraphyllia -- 142
125 - Stems complanate-foliate; stem leaves undulate -- Metaneckera
125 - Stems symmetrically foliate; leaves not undulate -- 126
126 - Alar cells inflated in well marked groups -- 127
126 - Alar cells mostly not differentiated, if so, not inflated -- 128
127 - Stem leaves deeply plicate; paraphyllia filamentous, abundant -- Palustriella
127 - Stem leaves not plicate; paraphyllia foliose, sparse to abundant -- Cratoneuron
128 - Paraphyllia with short cells, 1-3:1 -- 129
128 - Paraphyllia with elongate cells, more than 5:1 -- 140
129 - Cells of paraphyllia papillose -- 130
129 - Cells of paraphyllia smooth -- 134
130 - Leaf cells unipapillose -- 131
130 - Leaf cells pluripapillose -- 132
131 - Plants once-pinnate; leaf cells papillose on both surfaces -- Abietinella
131 - Plants 2-3-pinnate; leaf cells papillose only at back -- Thuidium
132 - Plants large, dioicous; leaf cells papillose only at back -- Thuidium
132 - Plants small, autoicous; leaf cells papillose on both surfaces -- 133
133 - Plants once-pinnate; leaves not incurved when dry; leaf cells strongly bulging; setae smooth -- Rauiella
133 - Plants 1-2-pinnate; leaves incurved when dry; leaf cells flat; setae smooth or papillose -- Cyrto-hypnum
134 - Papillae of leaf cells large, either forked or elongate and curved; leaves broadly ovate -- Thelia
134 - Papillae of leaf cells short, simple; leaves lanceolate to ovate-lanceolate -- 135
135 - Costa pellucid; leaves usually with hair-points -- Claopodium
135 - Costa opaque; leaves lacking hair-points -- 136
136 - Stem and branch leaves differentiated -- Haplocladium
136 - Stem and branch leaves uniform -- 137
137 - Leaf cells isodiametric or nearly so, hexagonal to short-rhombic -- 138
137 - Leaf cells elongate, oblong-rhombic to oblong-linear -- 139
138 - Capsules inclined, asymmetric; exostome teeth striate; plants largely western -- Pseudoleskea
138 - Capsules erect, symmetric; exostome teeth pale and papillose; plants largely eastern -- Leskea
139 - Capsules erect, symmetric; endostome segments narrow, not keeled -- Lescuraea
139 - Capsules inclined, asymmetric; endostome segments broader, keeled -- Pseudoleskea
140 - Leaf margins entire to serrulate -- Helodium
140 - Leaf margins strongly serrate in upper half -- 141
141 - Upper leaf cells short, 2-5:1; plants of southeastern US -- Climacium
141 - Upper leaf cells linear, more than 8:1; plants widespread -- Hylocomiastrum
142 - Plants whitish; leaves composed mostly of costa, multistratose, with small green cells enclosed between 2 layers of hyaline cells on both surfaces -- 143
142 - Plants greenish to blackish, rarely whitish; leaves usually with conspicuous lamina, if not green cells and hyaline cells of about equal size with only a single layer of hyaline cells on either side of the green cells -- 144
143 - Green cells in section 4-sided; plants terrestrial -- Leucobryum
143 - Green cells in section 3-sided; plants epiphytic -- Octoblepharum
144 - Leaf margins strongly incurved to involute, at least when dry -- 145
144 - Leaf margins plane to recurved -- 149
145 - Leaf margins incurved wet or dry -- 146
145 - Leaf margins incurved when dry, plane when moist -- 148
146 - Leaf cells papillose; costa with two stereid bands -- 147
146 - Leaf cells smooth; costa with one stereid band -- Indusiella
147 - Capsules exserted, operculate -- Weissia
147 - Capsules immersed to emergent, cleistocarpous -- Astomum
148 - Costa with single stereid band; peristome present -- Plaubelia
148 - Costa with two stereid bands; peristome absent -- Hyophila
149 - Plants minute, occurring on soil (or rarely rock), ephemeral, often with persistent protonemata; capsules immersed -- 150
149 - Plants mostly larger, occurring on various substrates, mostly not ephemeral, or if so, capsules exserted -- 161
150 - Capsules operculate -- 151
150 - Capsules cleistocarpous -- 152
151 - Exothecial cells collenchymatous -- Aphanorrhegma
151 - Exothecial cells not thickened at corners -- Physcomitrium
152 - Spores few per capsule, more than 100 µm in diameter -- 153
152 - Spores numerous per capsule, less than 60 µm in diameter -- 154
153 - Leaves broadly ovate or elliptic, abruptly narrowed to an awn; plants with slender, subterranean rhizomes -- Lorentziella
153 - Leaves oblong to lanceolate, acute to subulate; plants not rhizomatous -- Archidium
154 - Leaves ovate to broadly ovate, abruptly cuspidate to apiculate -- 155
154 - Leaves narrowly lanceolate to oblong; costa subpercurrent to subulate -- 157
155 - Leaf cells pluripapillose with C-shaped papillae; leaf margins revolute -- Phascum
155 - Leaf cells smooth or with 1-2 blunt, conical papillae; leaf margins plane to erect -- 156
156 - Plants bulbiform, occurring on soil; leaves very broad and deeply concave with a reflexed tip -- Acaulon
156 - Plants not bulbiform, occurring on the underside of quartz pebbles; leaves oblong-lanceolate to oblong-ovate, the tip not reflexed -- Aschisma
157 - Capsules pyriform with a conspicuous stomatose neck -- Bruchia
157 - Capsules globose to broadly elliptic without a conspicuously differentiated neck -- 158
158 - Costa long excurrent, at least on perichaetial leaves -- Pleuridium
158 - Costa subpercurrent -- 159
159 - Leaf margins spinose-serrulate throughout -- Ephemerum
159 - Leaf margins entire or serrulate above -- 160
160 - Leaves lanceolate -- Pseudephemerum
160 - Leaves oblong-lanceolate to obovate -- Physcomitrella
161 - Neck of capsules (apophysis) as wide or wider than upper portion (urn); occurring on dung and animal remains -- 162
161 - Neck of capsules considerably narrower than urn; occurring on various substrates -- 164
162 - Capsules dumb-bell shaped when mature; seta hyaline; restricted to the arctic -- Aplodon
162 - Capsules (at least the urn) cylindric; seta colored; widespread -- 163
163 - Apophyses narrowly pyriform, the same color or darker than the urn; peristome teeth joined in 4's, later in 2's, not chambered -- Tetraplodon
163 - Apophyses globose to turbinate, sometimes becoming umbrella-like, differentiated in color; peristome teeth sometimes approximate or fused in pairs, chambered -- Splachnum
164 - Leaves of two kinds, large lateral ones and smaller dorsal ones -- 165
164 - Leaves all of one kind -- 166
165 - Leaves bordered; plants erect, occurring along the Pacific coast -- Epipterygium
165 - Leaves unbordered; plants prostrate, restricted to southern Florida -- Racopilum
166 - Capsules cleistocarpous; plants rare -- 167
166 - Capsules operculate; plants rare to common -- 169
167 - Plants known only from New Hampshire; occurring on wet soil -- Bruchia
167 - Plants known from arctic and alpine tundra on animal-derived substrates -- 168
168 - Capsules broadest in lower half -- Voitia
168 - Capsules broadest in upper half -- Tetraplodon
169 - Cells with nodulose-wavy walls throughout the leaf, sometimes most conspicuous toward leaf base when upper cells short -- Racomitrium
169 - Cells without nodulose-wavy walls, or if present only near insertion -- 170
170 - Leaves with hyaline hair-points -- 171
170 - Leaves without hair-points, or if with hairpoints not hyaline -- 181
171 - Costa broad, filling 1/4 or more of the leaf base -- Campylopus
171 - Costa narrower -- 172
172 - Upper leaf cells densely pluripapillose with C-shaped papillae -- 173
172 - Upper leaf cells smooth or with low, indistinct papillae -- 174
173 - End walls of basal cells thickened; calyptrae large, mitrate and covering capsule -- Encalypta
173 - End walls of basal cells not thickened; calyptrae small, cucullate -- Tortula
174 - Cells smooth, lax, thin-walled, hexagonal to rhombic -- 175
174 - Cells obscurely papillose, firm-walled, rounded to quadrate -- 177
175 - Leaves not bordered -- Stegonia
175 - Leaves bordered -- 176
176 - Plants usually epiphytic; capsules erect -- Brachymenium
176 - Plants terrestrial or saxicolous; capsules inclined -- Bryum
177 - Plants occurring on trees -- Orthotrichum
177 - Plants occurring on rocks and soil -- 178
178 - Perichaetial leaves differentiated in size and shape; capsules immersed -- Schistidium
178 - Perichaetial leaves similar to upper vegetative leaves; capsule immersed or exserted -- 179
179 - Calyptrae scarcely longer than the operculum, cucullate or mitrate, smooth -- Grimmia
179 - Calyptrae large, covering the capsule to the middle or below, campanulate-mitrate, striate or plicate -- 180
180 - Leaves lanceolate; annuli none; calyptrae plicate -- Coscinodon
180 - Leaves ovate to obovate; annuli well developed; calptrae striate -- Jaffueliobryum
181 - Costa very broad, occupying 1/3-1/2 the leaf base and filling the subula (plants entirely acrocarpous) -- 182
181 - Costa narrower, or if broad then ending below the leaf apex and not filling it (or if broad then pleurocarpous) -- 187
182 - Alar cells well diffentiated -- 183
182 - Alar cells poorly differentiated -- 185
183 - Costa without guide cells or stereids, in transverse section with a median layer of green cells enclosed dorsally and ventrally with hyaline cells -- Paraleucobryum
183 - Costa nearly always with guide cells and stereids, without enclosed green cells -- 184
184 - Inner basal cells of leaf pale, enlarged, and broadly rectangular, extending upward along the costa; capsules smooth; annuli none; calyptrae not fringed -- Dicranodontium
184 - Inner basal cells not conspicuously differentiated along the costa; capsules furrowed; annuli compound; calyptrae usually fringed -- Campylopus
185 - Capsules with a neck at least as long as the urn; costa filling no more than 1/3 of the leaf base -- Trematodon
185 - Capsules with a short, inconspicuous neck; costa filling 1/2 or more of the leaf base -- 186
186 - Leaves 3.5-5.0 mm long; upper laminal cells elongate, 75-140 µm long; brood leaves absent -- Campylopodiella
186 - Leaves 2.0-3.0 mm long; upper laminal cells rectangular, 25-55 µm long; brood leaves usually present, often abundant -- Brothera
187 - Plants pleurocarpous (sporophytes lateral); stems mostly prostrate with lateral branches, often mat- forming, or stems prostrate with erect branches bearing terminal sporophytes (cladocarpous) -- 188
187 - Plants acrocarpous (sporophytes terminal); stems erect, not branched or occasionally branched beneath inflorescences -- 280
188 - Leaves bordered by elongate cells, sharply differentiated from shorter inner cells -- 189
188 - Leaves not bordered by elongate cells -- 191
189 - Plants epiphytic; border unistratose -- Daltonia
189 - Plants aquatic; border 2-5-stratose -- 190
190 - Margins serrate almost to base; leaves ovate-oblong to ovate-lanceolate, acuminate; plants of Oregon -- Limbella
190 - Margins serrulate; leaves ovate, often broadly so, bluntly acute; plants of eastern North America -- Platylomella
191 - Leaf cells papillose or prorulose -- 192
191 - Leaf cells smooth -- 205
192 - Leaves rugose and plicate -- Rhytidium
192 - Leaves not rugose, rarely plicate -- 193
193 - Leaf cells pluripapillose -- 194
193 - Leaf cells unipapillose or prorulose -- 198
194 - Papillae arranged in a row over the cell lumina; cells longer than 3:1 -- 195
194 - Papillae randomly arranged over the cells; cells more or less isodiametric -- 196
195 - Plants stiff, dark green to blackish; leaves ovate, plicate, cordate -- Papillaria
195 - Plants soft, bright green (when alive); leaves lanceolate, smooth, not cordate -- Barbella
196 - Leaf apices fragile -- Haplohymenium
196 - Leaf apices not fragile -- 197
197 - Leaves strongly inrolled when dry; marginal basal cells elongate, smooth; sporophytes terminal on branches -- Macromitrium
197 - Leaves loosely erect to contorted; marginal basal cells rounded, papillose; sporophytes lateral -- Anomodon
198 - Cells unipapillose over the lumina -- 199
198 - Cells prorulose -- 201
199 - Upper leaf cells linear-flexuose; uniseriate propagula common in leaf axils -- Henicodium
199 - Upper leaf cells short, 1-3:1; asexual reproduction absent or by branchlets -- 200
200 - Leaves ovate-lanceolate, narrowed to a nonpapillose, pale acumen, squarrose when moist -- Lindbergia
200 - Leaves oblong-ovate, bluntly acute, loosely erect and more or less complanate -- Stereophyllum
201 - Leaf cells short, 1-3:1 -- 202
201 - Leaf cells more than 5:1 -- 203
202 - Leaves appressed when dry, wide-spreading when moist; perichaetial leaves strongly differentiated; capsules immersed -- Cryphaea
202 - Leaves little altered when moist; perichaetial leaves scarcely differentiated; capsules exserted -- Lescuraea
203 - Plants epiphytic with inconspicuous, creeping, primary stem and erect secondary stems; costa subpercurrent -- Pireella
203 - Plants terrestrial and epiphytic, with primary and secondary stems not differentiated; costa ending well below the apex -- 204
204 - Leaves decurrent; setae rough; capsules inclined; plants largely terrestrial -- Bryhnia
204 - Leaves not decurrent; setae smooth; capsules erect; plants epiphytic or saxicolous -- Isothecium
205 - Leaf apices rounded-obtuse to truncate -- 206
205 - Leaf apices acuminate to bluntly acute -- 212
206 - Leaf apices truncate -- Neckeropsis
206 - Leaf apices rounded-obtuse -- 207
207 - Upper leaf cells less than 3:1 -- 208
207 - Upper leaf cells (not apical ones) more than 5:1 -- 209
208 - Plants strongly complanate, shiny, little altered when moist -- Homalia
208 - Plants at best weakly complanate, dull, strongly incurved when dry, erect when moist -- Leptodon
209 - Alar cells inflated -- 210
209 - Alar cells not at all inflated -- 211
210 - Plants strongly julaceous; leaves concave; occurring in or near streams -- Scleropodium
210 - Plants with loosely spreading leaves; leaves only slightly concave; occurring in fens -- Calliergon
211 - Costa ending in a spine -- Platyhypnidium
211 - Costa not projecting at apex -- Hygrohypnum
212 - Upper leaf cells 1-2:1 -- 213
212 - Upper leaf cells more than 5:1 -- 227
213 - Sporophytes terminal on erect branches; upper cells rounded -- 214
213 - Sporophytes lateral; upper cells rhombic to subquadrate -- 217
214 - Basal marginal cells short, rounded-quadrate -- 215
214 - Basal marginal cells elongate -- 216
215 - Upper leaf cells strongly bulging; leaves lanceolate; calyptrae hairy, mitrate -- Macrocoma
215 - Upper leaf cells flat; leaves oblong-lanceolate; calyptrae naked, cucullate -- Drummondia
216 - Inner basal leaf cells subquadrate to rounded; calyptrae short, plicate -- Groutiella
216 - Inner basal cells linear; calyptrae long, not plicate -- Schlotheimia
217 - Costa strongly flexuose above; leaf margins with multicellular teeth -- Herpetineuron
217 - Costa straight or faintly flexuose; leaf margins entire to serrulate -- 218
218 - Costa ending in the leaf apex -- 219
218 - Costa ending well below the leaf apex -- 223
219 - Upper leaf cells thick-walled, rounded-quadrate to elliptic -- 220
219 - Upper leaf cells firm-walled, short-oblong to rhombic -- 222
220 - Plants with clusters of axillary brood branchlets -- Leskeella
220 - Plants without brood branchlets -- 221
221 - Alar cells extending to the costa; inner basal cells not differentiated; peristome white -- Lindbergia
221 - Alar cells restricted in 5-6 rows along the margins, not reaching the costa; inner basal cells long rectangular; peristome yellow -- Pseudoleskeella
222 - Costa relatively narrow, less than 35 µm wide at base; plants terretrial -- Amblystegium
222 - Costa relatively broad, mostly more than 50 µm at base; plants aquatic -- Hygroamblystegium
223 - Plants with secondary stems erect and branched -- 224
223 - Plants without differentiated secondary stems, prostrate -- 225
224 - Leaf apices shortly acuminate; leaves more than 1 mm long; plants eastern -- Forsstroemia
224 - Leaf apices broadly acute; leaves less than 1 mm long; plants western -- Porotrichum (Bryolawtonia)
225 - Leaves acuminate, often homomallous -- Pseudoleskeella
225 - Leaves bluntly acute -- 226
226 - Leaves obliquely asymmetric at tip; exostome teeth cross-striate; plants boreal and arctic -- Myrinia
226 - Leaves symmetric; exostome teeth rudimentary; plants of southeastern North America -- Clasmatodon
227 - Plants bearing long, deciduous, flagelliform branches -- Pseudocryphaea
227 - Plants without flagelliform branches -- 228
228 - Plants with inconspicuous, creeping primary stems with reduced leaves and erect, leafy secondary stems -- 229
228 - Plants without differentiated stems -- 232
229 - Secondary stems mostly unbranched -- Jaegerina
229 - Secondary stems irregulary pinnate -- 230
230 - Costa toothed at back on secondary stem leaves; branch leaves acute -- Bestia
230 - Costa smooth at back; branch leaves acuminate -- 231
231 - Leaf margins revolute nearly throughout, serrate above, often with reflexed teeth; costa often with supplementary costae; western in distribution (disjunct in Newfoundland) -- Antitrichia
231 - Leaf margins reflexed, entire to serrulate; costa without supplementary costae; eastern in distribution -- Forsstroemia
232 - Plants aquatic, coarse; costa broad, more than 100 µm wide at base, bluntly excurrent -- 233
232 - Plants of various habitats; costa much narrower, ending below the apex to excurrent, if excurrent then finely so -- 234
233 - Costa about 1/3 the width of the leaf base; the lamina with multistratose streaks -- Donrichardsia
233 - Costa about 1/4 the width of the leaf base; the lamina unistratose throughout -- Hygroamblystegium
234 - One side of stems for entire length covered by reddish rhizoidal tomentum; leaves strongly plicate -- Tomentypnum
234 - Tomentum, if present, restricted to extreme base of stems; leaves plicate or not -- 235
235 - Leaves falcate-secund -- 236
235 - Leaves straight -- 248
236 - Stems with a hyalodermis -- 237
236 - Stems without a hyalodermis -- 239
237 - Leaves strongly plicate, distinctly denticulate in upper portion -- Sanionia
237 - Leaves striolate to plane, entire to slightly denticulate -- 238
238 - Alar cells inflated; plants occurring in streams -- Hygrohypnum
238 - Alar cells poorly differentiated; plants occurring in rich fens -- Limprichtia
239 - Plants of upland habitats; leaves plicate -- Brachythecium
239 - Plants of wet habitats; leaves not plicate -- 240
240 - Leaves keeled, distinctly to obscurely 3-ranked; endostome segments joined at tips -- Dichelyma
240 - Leaves not keeled or 3-ranked; endostome segments free -- 241
241 - Costa excurrent -- 242
241 - Costa subpercurrent -- 244
242 - Alar cells poorly differentiated -- Drepanocladus
242 - Alar cells abruptly inflated -- 243
243 - Leaf margins entire -- Drepanocladus
243 - Leaf margins finely denticulate -- Warnstorfia
244 - Leaf margins finely denticulate at apex -- Warnstorfia
244 - Leaf margins entire throughout -- 245
245 - Plants on rocks in mountain streams -- Hygrohypnum
245 - Plants in fens and seeps, not on rocks -- 246
246 - Cells in lower half of leaf porose; plants of the arctic -- Loeskypnum
246 - Cells not porose except at extreme insertion; plants widespread -- 247
247 - Stems with central strand -- Drepanocladus
247 - Stems without central strand -- Hamatocaulis
248 - Leaves 3-ranked, conduplicate -- Brachelyma
248 - Leaves not 3-ranked or conduplicate -- 249
249 - Plants pendulous from branches; stem leaves with capillary points; branch leaves recurved; plants restricted to southernmost Florida -- Zelometeorium
249 - Plants terrestrial to epiphytic, never pendulous; stem leaves with shorter points; branch leaves mostly not squarrose; plants mostly more northern -- 250
250 - Leaf cells long hexagonal, less than 8:1 -- 251
250 - Leaf cells linear, more than 10:1 -- 258
251 - Leaves broadly ovate, deeply concave; restricted to Alaska -- Myuroclada
251 - Leaves lanceolate to ovate, not or only slightly concave; widespread -- 252
252 - Plants epiphytic -- 253
252 - Plants terrestrial and saxicolous -- 254
253 - Leaf margins entire; leaf apex gradually acuminate; peristome double and reflexed -- Anacamptodon
253 - Leaf margins mostly toothed; leaf apex piliferous; peristome single to absent -- Fabronia
254 - Leaf apices piliferous -- Fabronia
254 - Leaf apices acute to acuminate -- 255
255 - Upper leaf cells thick-walled, with rounded ends; capsules erect -- Pseudoleskeella
255 - Upper leaf cells firm-walled, with pointed ends; capsules inclined -- 256
256 - Plants on soil in dry habitats, especially prairies -- Brachythecium
256 - Plants on logs and soil in mesic to wet habitats -- 257
257 - Leaves greater than 1 mm long -- Leptodictyum
257 - Leaves less than 1 mm long -- Amblystegium
258 - Plants attached to rocks in fast-flowing streams and beside waterfalls -- Platyhypnidium
258 - Plants in various habitats but not on rocks in fast-flowing water -- 259
259 - Plants terrestrial, large, coarse, erect; stems pinnately branched -- 260
259 - Plants various, prostrate to ascending, if erect then in wetlands; branching various -- 261
260 - Stem leaves ovate-lanceolate, acuminate to filiform, plicate; plants on litter in coniferous forests -- Trachybryum
260 - Stem leaves ovate-oblong, abruptly apiculate, not plicate; plants in lawns and gardens -- Pseudoscleropodium
261 - Leaves plicate -- 262
261 - Leaves not plicate -- 264
262 - Branches curved-ascending when dry -- Homalothecium
262 - Branches prostrate -- 263
263 - Leaf apices coarsely serrate; upper leaf cells thick-walled; alar cells well differentiated, quadrate; plants rigid -- Palamocladium
263 - Leaf apices entire to serrulate; upper leaf cells firm-walled; alar cells mostly differentiated, short-rectangular; plants soft -- Brachythecium
264 - Plants on tree trunks; calyptrae sparsely hairy; setae rough; plants of eastern US -- Homalotheciella
264 - Plants not on tree trunks except rarely at bases, if on trees plants of western North America; calyptrae naked; setae usually smooth, rarely rough -- 265
265 - Plants terete, at least at apex; leaves broadly oblong to ovate, concave to cucullate -- 266
265 - Plants with spreading leaves; leaves lanceolate, not or scarcely concave -- 272
266 - Leaves abruptly acuminate -- 267
266 - Leaves broadly acute to obtuse, sometimes with a minute apiculus -- 269
267 - Costa with one or more spines at the tip; plants of western North America -- Scleropodium
267 - Costa without spines at tip; plants widespread -- 268
268 - Leaf apex filiform, flat -- Cirriphyllum
268 - Leaf apex broader, twisted -- Bryoandersonia
269 - Leaves with minute apiculus -- 270
269 - Leaves not apiculate -- 271
270 - Plants green; basal leaf cells porose -- Loeskypnum
270 - Plants reddish; basal leaf cells not porose -- Sarmentypnum
271 - Leaves obtuse; plants occurring in fens and swamps; widespread -- Calliergon
271 - Leaves broadly acute; plants occurring on moist rocks and soil; Pacific coast -- Scleropodium
272 - Branch leaves with apical cells about 1/2 the length of those at midleaf -- Eurhynchium
272 - Branch leaves with apical cells scarcely shorter than those at midleaf -- 273
273 - Leaf apices twisted; stems often complanate-foliate -- Steerecleus
273 - Leaf apices flat; stems rarely complanate-foliate -- 274
274 - Leaves with channeled leaf apices from a concave base, with a narrow insertion -- Campylium
274 - Leaves without channeled leaf apices, the leaf base not concave or with a narrow insertion -- 275
275 - Alar cells numerous and quadrate with more on one side of the costa than the other, collenchymatous; plants of southernmost Florida -- Entodontopsis
275 - Alar cells few, symmetrically arranged, not collenchymatous; plants widespread -- 276
276 - Branch and stem leaves strongly differentiated; opercula long rostrate -- Eurhynchium
276 - Branch and stem leaves scarcely differentiated; opercula conic to apiculate -- 277
277 - Costa percurrent or nearly so -- 278
277 - Costa ending well below leaf apex -- 279
278 - Costa indistinct at midleaf, not toothed; setae smooth; propagula uniseriate, often formed on back of costa at apex -- Conardia
278 - Costa distinct throughout, toothed at back above; setae rough; propagula not present -- Brachythecium
279 - Leaves wide-spreading with entire margins; stems complanate-foliate, plants occurring in wet habitats -- Leptodictyum
279 - Leaves erect to spreading with serrulate margins, rarely entire; stems not complanate-foliate, plants occurring in various habitats -- Brachythecium
280 - Capsules large, sessile, asymmetric -- Diphyscium
280 - Capsules smaller, usually exserted, symmetric -- 281
281 - Costa ridged at back -- 282
281 - Costa smooth or toothed at back, not ridged -- 283
282 - Leaf cells rounded-oblate -- Dryptodon
282 - Leaf cells long-rectangular, more than 5:1 -- Dicranum
283 - Conspicuous clusters of dark rhizoids obscuring the stem -- 284
283 - Rhizoids inconspicuous or if obvious, never obscuring the stem -- 287
284 - Leaf cells strongly unipapillose on both surfaces -- Aulacomnium
284 - Leaf cells smooth or prorulose -- 285
285 - Leaves narrowly lanceolate from an ovate base -- Anacolia
285 - Leaves ovate to broadly elliptic -- 286
286 - Rhizoidal (macronematal) initials in longitudinal rows; endostome fused into a dome -- Cinclidium
286 - Rhizoidal initials not in longitudinal rows; endostome segments free -- Rhizomnium
287 - Plants blackish, occurring on wet rocks usually near streams or the sea, never with propagula -- 288
287 - Plants greenish, occurring in various habitats, rarely on wet rocks by streams, with or without propagula -- 290
288 - Leaf bases with submarginal band of elongate cells -- Scouleria
288 - Leaf bases without differentiated submarginal cells -- 289
289 - Leaf margins incurved -- Grimmia
289 - Leaf margins plane to recurved -- Schistidium
290 - Hyaline basal cells extending up the margins farther than at the costa, forming a V-shaped area -- 291
290 - Hyaline basal cells if present extending more or less equally up the margins as costa or farther up the costa -- 293
291 - Upper cells bulging but not papillose -- Luisierella
291 - Upper cells pluripapillose -- 292
292 - Leaves squarrose-recurved from an erect base when moist; leaf margins serrulate above; sporophytes lateral -- Pleurochaete
292 - Leaves erect-spreading to spreading from an erect base when moist; leaf margins entire to notched; sporophytes terminal -- Tortella
293 - Plants glaucous, bluish-green -- Saelania
293 - Plants not glaucous or bluish -- 294
294 - Leaves bordered by 2 or more rows of elongate cells -- 295
294 - Leaves unbordered or if bordered then by only a single row of somewhat elongate cells, or by short cells -- 309
295 - Leaf margins entire -- 296
295 - Leaf margins toothed, sometimes obscurely so -- 300
296 - Leaf cells longer than 3:1 -- 297
296 - Leaf cells 1-2:1 -- 298
297 - Leaf cells in oblique rows; leaves rounded-obtuse, bluntly apiculate -- Pseudobryum
297 - Leaf cells not in obvious rows; leaves various -- Bryum
298 - Rhizoidal (macronematal) initials in longitudinal rows; endostome fused to a dome -- Cinclidium
298 - Rhizoidal initials not in longitudinal rows; endostome segments free -- 299
299 - Leaves bluntly acute; border unistratose; stems blackish; stomates superficial -- Cyrtomnium
299 - Leaves emarginate, rounded-apiculate; border various; stems reddish; stomates immersed -- Rhizomnium
300 - Leaves lanceolate from an expanded base, the base with numerous, abruptly hyaline cells -- Syrrhopodon
300 - Leaves without expanded base, without hyaline cells -- 301
301 - Leaf margins with paired teeth -- 302
301 - Leaf margins with single teeth -- 304
302 - Leaf cells strongly bulging -- Trachycystis
302 - Leaf cells flat -- 303
303 - Some leaves with low, inconspicuous lamellae; costa in transverse section with two stereid bands; peristome of 32 small teeth attached at tips to a tympanum -- Atrichum
303 - No leaves with lamellae; costa with or without a single stereid band; exostome of 16 free teeth -- Mnium
304 - Leaves rugose wet or dry; plants restricted to Pacific Northwest -- Roellia
304 - Leaves flat when wet, contorted but not rugose when dry; plants widespread -- 305
305 - Leaf cells shorter than 2:1 -- Plagiomnium
305 - Leaf cells 3:1 or more -- 306
306 - Stems rosulate-foliate, occurring erect from a horizontal underground stem; sporophytes often clustered -- Rhodobryum
306 - Stems foliate throughout, without rhizome-like connections between erect stems; sporophytes not clustered -- 307
307 - Leaf cells in oblique rows; leaves rounded-obtuse, apiculate -- Pseudobryum
307 - Leaf cells not in obvious rows; leaves broadly acute to acuminate -- 308
308 - Capsules erect and symmetric; endostome with a high basal membrane, segments lacking or rudimentary, cilia absent -- Brachymenium
308 - Capsules inclined and asymmetric; endostome with a keeled basal membrane, keeled and perforate segments, and usually with cilia -- Bryum
309 - Leaf margins with paired teeth -- 310
309 - Leaf margins with single teeth or entire -- 315
310 - Leaf bases with abruptly differentiated colorless cells (cancellinae); propagula borne on costa near apex -- Syrrhopodon
310 - Leaf bases without cancellinae; propagula absent -- 311
311 - Leaf cells smooth -- 312
311 - Leaf cells prorulose or with fine cuticular ridges -- 313
312 - Leaves elliptic to ovate-elliptic -- Mnium
312 - Leaves linear-lanceolate -- Pyrrhobryum
313 - Upper leaf cells with cuticular ridges; stems triangular in transverse section -- Plagiopus
313 - Upper leaf cells prorulose; stems round in transverse section -- 314
314 - Leaves crispate when dry -- Bartramia
314 - Leaves straight when dry -- Philonotis
315 - Leaf cells strongly bulging on one or both surfaces, not papillose -- 316
315 - Leaf cells flat, smooth or papillose, or if bulging then papillose -- 318
316 - Leaf laminae bistratose -- Timmiella
316 - Leaf laminae unistratose -- 317
317 - Plants with sheathing leaf bases -- Timmia
317 - Plants without sheathing leaf bases -- Bryobrittonia
318 - Leaves with abruptly expanded, sheathing leaf bases -- 319
318 - Leaves with leaf bases not or only gradually expanded, rarely sheathing -- 326
319 - Leaf cells papillose (at least on sheath) or prorulose -- 320
319 - Leaf cells smooth -- 321
320 - Leaf cells papillose over the lumina -- Timmia
320 - Leaf cells prorulose -- Bartramia
321 - Upper leaf cells quadrate -- 322
321 - Upper leaf cells short-rectangular -- 323
322 - Capsules inclined and asymmetric, strumose; plants widespread -- Oncophorus
322 - Capsules erect, symmetric, not strumose; plants restricted to southwestern US -- Symblepharis
323 - Awns roughened throughout by projecting cell ends -- Trichodon
323 - Awns smooth or only rough at apex -- 324
324 - Capsules with neck as long as or longer than the urn -- Trematodon
324 - Capsules with neck much shorter than the urn -- 325
325 - Capsules erect, cylindric, smooth; peristome teeth irregularly perforate or deeply cleft into terete, sometimes filiform divisions -- Ditrichum
325 - Capsules inclined, oblong, smooth or furrowed, if erect then furrowed; peristome teeth flat, split 1/2 way down, vertically pitted -- Dicranella
326 - Alar cells enlarged, colored, or inflated -- 327
326 - Alar cells scarcely differentiated -- 333
327 - Upper and median leaf cells with coarse, irregular cuticular ridges, resembling papillae in transverse section; capsules cylindric, smooth, erect -- 328
327 - Leaf cells without cuticular ridges; capsules various -- 329
328 - Leaves with clusters of spherical propagula at leaf apex; leaf margins bistratose -- Grimmia
328 - Leaves without propagula; leaf margins unistratose -- Dicranoweisia
329 - Costa with 2 stereid bands -- Dicranum
329 - Costa without stereids -- 330
330 - Capsules curved, strumose; plants on alpine rocks -- Kiaeria
330 - Capsules erect, not strumose; plants widespread -- 331
331 - Capsules cylindric; plants usually terrestrial or on tree trunks, rarely on rock -- Dicranum
331 - Capsules short, obovoid to pyriform; plants on rocks -- 332
332 - Capsules ribbed when dry; peristome vertically pitted-striolate below -- Arctoa
332 - Capsules smooth when dry; peristome papillose -- Blindia
333 - Leaf cells smooth -- 334
333 - Leaf cells papillose or prorulose -- 398
334 - Asexual propagula borne on the leaf surfaces -- Rhachithecium
334 - Asexual propagula absent, axillary or on leaf apices or specialized structures -- 335
335 - Leaves ovate to obovate, broadly obtuse, with the costa ending below the leaf apex -- 336
335 - Leaves linear, ovate-lanceolate, ligulate to ovate, acuminate to acute or awned, with costa ending below the apex to excurrent -- 342
336 - Leaf apices cucullate -- Globulinella
336 - Leaf apices not cucullate -- 337
337 - Plants with large, multicellular propagula in leaf axils; leaves obovate, with cilia on the basal margins -- Oedipodium
337 - Plants without axillary propagula; leaves ovate to spatulate, eciliate -- 338
338 - Plants small and bulbiform, on dry soil; leaves concave and imbricate -- Stegonia
338 - Plants small to medium-sized, never bulbiform, on moist soil; leaves flat to concave, mostly not imbricate -- 339
339 - Leaf cells short-rectangular, lax, thin-walled; capsules erect -- 340
339 - Leaf cells long-hexagonal, firm-walled; capsules inclined to horizontal -- 341
340 - Apical marginal leaf cells short-rhombic, oblong- hexagonal internally; capsules without a distinct neck; plants of southern US -- Splachnobryum
340 - Apical marginal leaf cells laxly rectangular, similar to internal ones; capsules with well differentiated neck; plants northern -- Tayloria
341 - Plants whitish-green, terete; upper leaf cells long, 7-9:1 -- Anomobryum
341 - Plants reddish or green, not terete; upper cells shorter, 2-6:1 -- Bryum
342 - Leaves oblong, lingulate to ovate -- 343
342 - Leaves lanceolate to linear -- 368
343 - Leaf cells rounded to quadrate, more or less isodiametric -- 344
343 - Leaf cells short-rectangular to linear -- 353
344 - Leaf bases with abruptly differentiated, hyaline cells (cancellinae); leaf apices often with propagula -- Calymperes
344 - Leaf bases without cancellinae although sometimes gradually hyaline; leaf apices without propagula -- 345
345 - Costa excurrent to ending in the cusp; leaf apex cuspidate to piliferous -- 346
345 - Costa subpercurrent; leaf apex broadly acute or obtuse to rarely mucronate -- 349
346 - Leaf apices piliferous -- Desmatodon
346 - Leaf apices cuspidate -- 347
347 - Plants with rhizoidal tubers, known only from Louisiana; capsules unknown -- Tortula (Chenia)
347 - Plants lacking tubers, widespread in the north; capsules exserted -- 348
348 - Capsules 0.4-0.8 mm long, obovoid; spores more than 20 µm in diameter; peristome absent or rudimentary; plants boreal-temperate -- Pottia
348 - Capsules 2.5-3.5 mm long, cylindric; spores less than 20 µm in diameter; peristome well developed with twisted teeth from a basal membrane; plants of tundra -- Crumia
349 - Peristome teeth four; propagula cups borne on apices of sterile shoots -- Tetraphis
349 - Peristome teeth 16; propagula cups absent -- 350
350 - Leaves homomallous, broadly oblong to oblong- ovate, subacute to obtuse -- Aulacomnium
350 - Leaves not homomallous, oblong to lanceolate, mucronate to acuminate -- 351
351 - Leaves broadly to narrowly lanceolate; peristome double -- Meesia
351 - Leaves broadly oblong to spatulate; peristome single -- 352
352 - Costa in transverse section with 2 stereid bands -- Barbula
352 - Costa in transverse section with 1 stereid band -- Scopelophila
353 - Plants filiform, julaceous (if costa not excurrent see also Anomobryum) -- Aongstroemia
353 - Plants coarser, not julaceous -- 354
354 - Capsules horizontal to pendulous -- 355
354 - Capsules erect -- 360
355 - Capsules curved, asymmetric -- 356
355 - Capsules straight, symmetric -- 357
356 - Exostome shorter than and alternate with endostome -- Plagiobryum
356 - Exostome longer than and opposite to endostome -- Funaria
357 - Capsules ovate, less than 1 mm long; stomates none; endostome fused to exostome, cilia none -- Discelium
357 - Capsules cylindric to ovate, usually greater than 1 mm long; stomates present; endostome free of exostome, cilia mostly present -- 358
358 - Leaf cells in oblique rows -- Plagiobryum
358 - Leaf cells not in obvious oblique rows -- 359
359 - Leaf cells 4:1 or less -- Bryum
359 - Leaf cells 5:1 or longer -- Pohlia
360 - Peristome absent -- 361
360 - Peristome present -- 363
361 - Calyptrae 4-angled, sheathing the entire capsule until after dehiscence -- Pyramidula
361 - Calyptrae not angled, not sheathing or persistent -- 362
362 - Capsules subcylindric or narrrowly pyriform; annuli none; exothecial cells oblong to oblong-linear; calyptrae inflated- cucullate -- Entosthodon
362 - Capsules urceolate to broadly pyriform; annuli present; exothecial cells irregularly hexagonal; calyptrae inflated-mitrate -- Physcomitrium
363 - Peristome of endostome only, without a center line on the outer surface -- Mielichhoferia
363 - Peristome double or of exostome only, with a center line on the outer surface -- 364
364 - Plants with scarcely differentiated neck -- 365
364 - Plants with well-differentiated neck (apophysis) -- 366
365 - Plants of arctic tundra -- Funaria
365 - Plants of British Columbia and south -- Entosthodon
366 - Urns black, sometimes with yellow apophyses -- Tetraplodon
366 - Urns and apophyses green to brown -- 367
367 - Setae pale greenish-white, slender; costa filling the acumen; plants of eastern North America -- Splachnum
367 - Setae brownish, stout to slender; costa ending below the leaf apex; plants of western and northern North America -- Tayloria
368 - Leaves conspicuously 4-ranked -- Conostomum
368 - Leaves not conspicuously ranked (if 3-ranked see Meesia) -- 369
369 - Leaf cells short, 1(-2):1, rounded to quadrate -- 370
369 - Leaf cells long, (3-)4:1 or longer, rectangular to long-hexagonal -- 386
370 - Perichaetial leaves strongly differentiated, with an awn as long as the lamina; leaves bistratose -- Diphyscium
370 - Perichaetial leaves slightly or not differentiated, never long awned; leaves uni- to multistratose -- 371
371 - Capsules distinctly 8 or 16 ribbed and furrowed -- 372
371 - Capsules smooth or indistictly furrowed when dry but without distinct ribs -- 378
372 - Calyptrae mitrate -- 373
372 - Calyptrae cucullate -- 375
373 - Calyptrae hairy -- Ulota
373 - Calyptrae naked -- 374
374 - Annuli none; calyptrae plicate -- Orthotrichum
374 - Annuli compound; calyptrae not plicate -- Brachydontium
375 - Setae cyneous; plants rare, forming tight cushions on alpine slopes -- Oreas
375 - Setae erect (but sometimes twisted); plants various but not as above -- 376
376 - Capsules abruptly bent at the seta-capsule junction and horizontal, often becoming purple-red when mature -- Ceratodon
376 - Capsules erect to suberect and becoming brown when mature -- 377
377 - Peristome teeth divided to half their length; capsules cylindric to ovate-cylindric, ca - 2 mm long; plants of Pacific Northwest -- Cynodontium
377 - Peristome teeth undivided; capsules ovoid, less than 1 mm long; plants of eastern and midwestern US and maritime Canada -- Rhabdoweisia
378 - Capsules with an erect, elongate, well defined neck; peristome double -- Meesia
378 - Capsules with a short, inconspicous neck; peristome single -- 379
379 - Capsules inclined -- 380
379 - Capsules erect -- 381
380 - Capsules less than 1 mm long, black, not strumose; leaf margins unistratose; plants of rich fens -- Catoscopium
380 - Capsules 1.5-2.0 mm long, pale, strumose; leaf margins bistratose; plants on moist soil, rocks and logs - -- Oncophorus
381 - Capsules immersed to short-exserted -- Grimmia
381 - Capsules long-exserted -- 382
382 - Calyptrae mitrate -- 383
382 - Calyptrae cucullate, not plicate -- 384
383 - Calyptrae plicate; setae straight -- Ptychomitrium
383 - Calyptrae not plicate; setae cygneous -- Campylostelium
384 - Costa with 1 stereid band; leaf margins bistratose -- Trichostomopsis
384 - Costa with 2 stereid bands; leaf margins unistratose -- 385
385 - Leaves lanceolate from a somewhat expanded base -- Didymodon
385 - Leaves oblong -- Barbula
386 - Leaves subulate -- 387
386 - Leaves acute to acuminate -- 394
387 - Capsules curved and asymmetric -- Dicranella
387 - Capsules straight, symmetric, although sometimes inclined to pendulous -- 388
388 - Setae flexuose-curved to cygneous -- 389
388 - Setae straight, but sometimes spirally- twisted -- 391
389 - Setae more 10 mm long; plants more than 5 mm tall; leaves more than 4 mm long; capsules pyriform -- Leptobryum
389 - Setae less than 5 mm long; plants less than 3 mm tall; leaves less than 2 mm long; capsules hemispheric -- 390
390 - Plants ephemeral, on soil in Florida; setae stout curved at apex, not twisted; capsules eperistomate -- Eccremidium
390 - Plants perennial, on rock, not in Florida; setae slender, twisted; capsules peristomate -- Seligeria
391 - Peristome double; plants arctic -- Pseudoditrichum
391 - Peristome single; plants widespread -- 392
392 - Capsules ovoid; plants on calcareous rocks -- Seligeria
392 - Capsules oblong to cylindric; plants generally on soil -- 393
393 - Capsules long cylindric; peristome teeth divided to base, terete, papillose -- Ditrichum
393 - Capsules short cylindric; peristome teeth divided half their length, flat, vertically pitted- striolate -- Dicranella
394 - Costa occupying 1/2 or more of leaf base; capsules curved and asymmetric, elongate-pyriform from a neck as long as the urn -- Amblyodon
394 - Costa occupying less than 1/4 the leaf base; capsules straight and symmetric, without conspicuous neck -- 395
395 - Plants small, less than 2 mm high, gregarious, occurring on calcareous rocks; capsules ovate -- Seligeria
395 - Plants larger, mostly more than 5 mm, in tufts occurring on various substrates; capsules cylindric -- 396
396 - Leaves flexuose-twisted when dry; capsules erect; plants occurring in the southern Appalachians and California -- Orthodontium
396 - Leaves erect, little altered when dry; capsules erect or inclined; plants widespread -- 397
397 - Capsules terminal, inclined to pendent; peristome double; leaves usually more than 1 mm long, sometimes with axillary propagula -- Pohlia
397 - Capsules appearing lateral, erect; peristome single; leaves less than 1 mm long, never with propagula -- Mielichhoferia
398 - Leaves bistratose throughout, ligulate to oblong, obtuse; perichaetial leaves long awned -- Diphyscium
398 - Leaves unistratose, or if bistratose then not ligulate to oblong; perichaetial leaves not so differentiated -- 399
399 - Leaf cells rectangular, prorulose; capsules globose, rugulose to furrowed when dry -- 400
399 - Leaf cells rounded-quadrate; uni- to pluripapillose; capsules ovate to cylindric, smooth or furrowed -- 403
400 - Leaves strongly ranked -- Conostomum
400 - Leaves not conspicuously ranked -- 401
401 - Capsules erect, or if pendent then from curvature of seta, symmetric, rugulose when dry; peristome reduced to a low membrane -- Bartramidula
401 - Capsules strongly inclined, asymmetric, furrowed; peristome better developed -- 402
402 - Leaves unistratose; plants on soil and rocks in at least periodically wet habitats, often with innovative branches beneath inflorescences -- Philonotis
402 - Leaves bistratose at least at margins; plants on banks and cliffs in mesic habitats, without innovative branches -- Bartramia
403 - Leaf cells appearing papillose from slightly thickened walls between cells (not prorulose) -- 404
403 - Leaf cells papillose over the lumina -- 405
404 - Leaves crispate when dry; capsules long exserted, cylindric; plants usually occurring on logs -- Dicranoweisia
404 - Leaves erect, straight to curved; capsules immersed to short exserted, ovate-cylindric; plants occurring on rocks -- Grimmia
405 - Leaf cells collenchymatous and stellate -- 406
405 - Leaf cells not thickened in the corners or if so merely rounded and not stellate -- 407
406 - Leaf cells unipapillose; leaves not recurved -- Aulacomnium
406 - Leaf cells pluripapillose; leaves recurved -- Geheebia
407 - Leaves with abruptly differentiated hyaline cells occupying most of the leaf base (cancellinae) and with an intramarginal border of elongate cells (teniolae), at least in lower part of leaf; usually with propagula on leaf apex -- Calymperes
407 - Leaves without cancellinae, or if present then never with teniolae; propagula never on leaf apices but sometimes elsewhere on leaves or in axils -- 408
408 - Plants with propagula borne terminally on specialized stalks from stem apices -- Aulacomnium
408 - Plants with or without various means of asexual reproduction but these never borne on stalks from the stem apices -- 409
409 - Plants occurring on tree trunks or bare rock, with immersed to shortly exserted, often ribbed capsules -- 410
409 - Plants usually occurring on soil, if on rocks or trees then capsules long exserted and mostly unribbed (or plants sterile) -- 412
410 - Calyptrae cucullate, not plicate, naked; occurring on wet rocks -- Amphidium
410 - Calyptrae mitrate, plicate, usually hairy; occurring on tree trunks and dry rocks -- 411
411 - Leaves usually crispate to contorted when dry; basal marginal cells with thickened transverse walls; stomates superficial; capsules shortly exserted -- Ulota
411 - Leaves usually little altered when dry; basal marginal cells not differentiated; stomates immersed or superficial; capsules immersed to shortly exserted -- Orthotrichum
412 - Costa in transverse-section more or less homogeneous, without differentiated stereids -- 413
412 - Costa in transverse-section with differentiated stereid bands -- 417
413 - Leaf cells with C-shaped papillae; leaves broadly spatulate -- Gymnostomiella
413 - Leaf cells with simple, conic papillae; leaves various but not broadly spatulate -- 414
414 - Upper leaf cells with 4-7 small, conic papillae -- Zygodon
414 - Upper leaf cells with 3 or fewer, simple to branched papillae -- 415
415 - Leaves less than 0.6 mm long, ligulate, rounded- obtuse; rare plants of calcareous rocks; annuli of 2-3 rows of well-differentiated cells -- Gyroweisia
415 - Leaves more than (0.7-)1.5 mm long, lanceolate to ovate, acuminate to obtuse; annuli poorly differentiated -- 416
416 - Leaves typically crispate to contorted when dry; basal marginal cells with thickened transverse walls; capsules shortly exserted; calyptrae hairy -- Ulota
416 - Leaves usually little altered when dry; basal marginal cells not differentiated; capsules immersed to shortly exserted; calyptrae naked (species with contorted leaves) to hairy (species with unaltered leaves) -- Orthotrichum
417 - Costa with a single, dorsal stereid band -- 418
417 - Costa with both dorsal and ventral stereid bands -- 429
418 - Calyptrae campanulate-mitrate, covering entire capsule, often lobed at base; basal leaf cells with thickened transverse walls -- Encalypta
418 - Calyptrae cucullate, covering only operculum and capsule apex, unlobed at base; basal leaf cells usually without thickened transverse walls -- 419
419 - Leaves linear-lanceolate to lanceolate, never with hair points; leaf margins recurved to plane; leaf cells with papillae conic, clavate or branched, rarely C-shaped -- 420
419 - Leaves broadly lanceolate (from revolute leaf margins), lingulate or oblong-ovate, sometimes with hair points; leaf margins recurved to strongly revolute; leaf cells with papillae stellate from a stipitate base to C-shaped -- 424
420 - Leaf cells with 4-7 widely spaced, small, conic papillae; elliptic propagula present in leaf axils; peristome double; plants usually occurring on trees, rarely on rock -- Zygodon
420 - Leaf cells with 1-3(-4) closely set, simple to branched papillae; propagula absent; peristome single or absent; plants occurring on soil and rocks -- 421
421 - Leaf margins serrulate above; capsules erect to inclined, often furrowed and strumose; peristome vertically pitted-striolate -- Cynodontium
421 - Leaf margins entire; capsules erect, never furrowed or strumose; peristome, when present, papillose -- 422
422 - Basal leaf cells lax and hyaline; upper leaf margins bistratose throughout; peristome present -- Trichostomopsis
422 - Basal leaf cells firm-walled, pale but not hyaline; upper leaf margins unistratose or irregularly bistratose; peristome absent -- 423
423 - Stem monopodially branched; archegonia on short, lateral branches; stem transverse section rounded- triangular -- Anoectangium
423 - Stem sympodially branched; archegonia terminal on main stem; stem transverse section round -- Gymnostomum
424 - Leaves with an intramarginal band of enlarged, smooth, often orange cells -- Crumia
424 - Leaves without differentiated intramarginal cells but sometimes with smooth marginal cells, these not enlarged -- 425
425 - Leaves narrowly lanceolate; leaf margins erect and bistratose -- Trichostomopsis
425 - Leaves oblong, lingulate to ovate; leaf margins plane to revolute, unistratose or if bistratose then always revolute -- 426
426 - Upper leaf margins broadly revolute to spirally revolute, with cells often more strongly chlorophyllose than median cells -- Pseudocrossidium
426 - Upper leaf margins plane to revolute, with cells undifferentiated or paler than median cells -- 427
427 - Leaves unbordered; peristome none or rudimentary -- Pottia
427 - Leaves often bordered by smooth cells; peristome present -- 428
428 - Peristome teeth united in a high or rarely low, tubular basal membrane, spirally twisted above; cells of adaxial (upper) surface of costa similar to or smaller than laminal cells in transverse section -- Tortula
428 - Peristome teeth free or rarely united in a low basal membrane, erect to slightly twisted above; cells of adaxial surface of costa mostly larger than or otherwise differentiated from laminal cells in transverse section -- Desmatodon
429 - Leaf margins abruptly serrate at the shoulder -- Eucladium
429 - Leaf margins entire at shoulders -- 430
430 - Leaf cells with numerous (more than 7), minute, elliptic papillae over the walls as well as the lumina -- Amphidium
430 - Leaf cells with fewer than 7, larger, round papillae only over the lumina -- 431
431 - Leaf margins toothed above -- 432
431 - Leaf margins entire or roughened with projecting papillae -- 436
432 - Laminae bistratose; margins unistratose -- Rhexophyllum
432 - Laminae unistratose; margins uni- or bistratose -- 433
433 - Leaf cells bulging, mamillose to unipapillose -- Dichodontium
433 - Leaf cells plane, pluripapillose -- 434
434 - Stems with central strand -- Bryoerythrophyllum
434 - Stems without central strand -- 435
435 - Stems with hyalodermis; adaxial (upper) surface of costa with enlarged, papillose epidermal cells -- Paraleptodontium
435 - Stems without hyalodermis; adaxial surface of costa with small, smooth cells -- Leptodontium
436 - Leaves at extreme apex with large, curved, projecting papillae -- Dichodontium
436 - Leaves at extreme apex with margins entire or papillose-crenulate -- 437
437 - Stems triquetrous, especially when moist; leaf cells unipapillose, the papillae sometimes branched; plants of California -- Triquetrella
437 - Stems without ranked leaves; leaf cells pluripapillose; plants widespread -- 438
438 - Stems without central strand, in transverse section with largest cells in middle of section -- Oxystegus
438 - Stems with central strand, or if poorly developed in transverse section at least with largest cells not in middle of stem -- 439
439 - Leaf margins plane to erect -- 440
439 - Leaf margins recurved to revolute, at least near midleaf or below -- 443
440 - Stems with hyalodermis -- Trichostomum
440 - Stems without hyalodermis, epidermal cells small -- 441
441 - Leaf apices subtubulose; upper leaf cells with 1-2 large, centered, multiplex papillae -- Tuerckheimia
441 - Leaf apices flat; upper leaf cells with 3-6 small, scattered, simple, blunt papillae -- 442
442 - Perichaetia and sporophytes lateral; leaves 2.2-3.0 mm long; axillary hairs of 15-20 cells -- Molendoa
442 - Perichaetia and sporophytes terminal; leaves less than 2.0 mm long; axillary hairs of 8-10 cells -- Gymnostomum
443 - Peristome none; leaves recurved only on one side -- Hymenostylium
443 - Peristome usually present; leaves recurved on both sides -- 444
444 - Axillary hairs with a brown, slender basal cell; laminal cells well defined in surface view; leaves usually lanceolate; cells of abaxial (back) surface of costa quadrate to short-oblong, rarely elongate; basal laminal cells usually little differentiated, green and short-rectangular -- Didymodon
444 - Axillary hairs with all cells hyaline; laminal cells obscure in surface view; leaves usually ovate to oblong; cells of abaxial surface of costa oblong to elongate; basal laminal cells usually strongly differentiated, hyaline and elongate -- Barbula
Vitt, Dale & Buck, William. (1992). Key to the moss genera of North America north of Mexico. Contribution to the University of Michigan Herbarium. 18. 43-72.
This key works with Mosses of Eastern North America, Howard A. Crum and Lewis E. Anderson, 1982, Columbia University Press
Errors or improvements? Contact Jeff at info@DigitalNaturalist.info.
last update 2025-May-9