Read each statement in order. If it doesn't fit go to the next grouping. Additional usage notes at bottom.
D- Plant with leaves of regular shape, often in 2 ranks...LEAFY liverworts
C- Opaque thalloid plant with internal air chambers or air-channels; rhizoids often pegged; setae very short or lacking...COMPLEX thalloid liverworts
B- Translucent thalloid plant; lacking air chambers, air-channels or pegged rhizoids; setae very long...SIMPLE thalloid liverworts
A- Strap-shaped or rosette-like thalloid plant; deep blue-green from cyanobacteria; sporophytes long cylindrical with stomata & columella...HORNWORTS
1- Sporophytes short, fusiform, horizontal, & scarcely exserted, thallus small (~1 cm)...Notothylas orbicularis
1- Sporophytes linear, erect, exserted; thallus larger (>1 cm) - 2
2- Spores black; thallus with crenate-crispate margins, dorsal lamellae & cavities...Anthoceros (2)
2- Spores yellow; thallus with entire margins; lacking lamellae & interior cavities...Phaeoceros laevis
C1 - Thallus rosette (or hemi-rosette) with dichotomous lobes; sporophytes embedded in thallus.
1- Plants typically floating with purplish, sword-like, serrulate ventral scales; thallus midline distinct to base of thallus...Ricciocarpus natans
1- Plants terrestrial; thallus midline restricted to apices of thallus...Riccia (7)
C2 - Thallus rolled into blackish-purple, worm-like tubes when dry; epidermis commonly smooth; carpocephala elevated & arising from apical notch.
1- Epidermal pores surrounded by 4-5 concentric rings of cells; thallus margins crenulate; carpocephala distinctly lobed...Reboulia hemisphaerica
1- Epidermal pores surrounded by 1-3 concentric rings of cells - 2
2- Sporophytes enclosed in lanceolate, hyaline scales; pores inconspicuous; antheridia adjacent to archegonia...Asterella tenella
2- Sporophytes enclosed in scales; antheridia distant from archegonia in most species...Mannia (3)
C3 - Thallus with gemmae receptacles
1- Gemmae receptacles cup-shaped; pores of dorsal epidermis compound (barrel-shaped)...Marchantia (3)
1- Gemmae receptacles crescent-shaped; pores of dorsal epidermis simple; greenhouse weed...Lunularia cruciata
C4 - Thallus with scales distinctively protruding from below.
1- Thallus usually in rosettes or hemi-rosettes; apical impressed, dorsal midline; epidermal pores obscure; sporophytes deeply sunken in thallus...Riccia (7)
1- Thallus not in rosettes & lacking dorsal midline; sporophytes in elevated carpocephalum - 2
2- Archegonia & carpocephala arising from dorsal crypt behind apex; epidermal pores strongly stellate....Clevea hyalina
2- Archegonia & carpocephala arising from apical notch; epidermal pores simple - 3
3- Sporophytes enclosed in lanceolate, hyaline scales (pseudoperianth remnants); antheridia adjacent to archegonia...Asterella tenella
3- Sporophytes enclosed in scales; antheridia distant from archegonia in most species...Mannia (3)
C5 - Thallus with air pores on dorsal surface (distinct to indistinct).
1c- Polygonal surface areolation strikingly obvious to naked eye; pores simple & on elevated, white cones composed of 4-5 rings of cells...Conocephalum salebrosum
1b- Polygonal surface areolation evident with hand-lens - 2
2- Ventral scales in 4 rows & appendiculate; antheridial disk stalked; carpocephala deeply lobed; circular gemmae cups common...Marchantia (3)
2- Ventral scales in 2 rows - 3
3- Ventral scales purple & appendiculate; air chambers of thallus in 1 layer with filaments...Marchantia quadrata
3- Ventral scales hyaline & appendiculate; thallus wing thick, plane & incurved (dry); crescent shaped gemmae cups common...Lunularia cruciata
1a- Polygonal surface areolation indistinct; ventral scales in 2 rows, appendiculate & purple - 4
4- Pores simple & surrounded by 4-5 rings of cells; thallus margins crenulate; carpocephala divided into discrete lobes...Reboulia hemisphaerica
4- Pores simple & surrounded by 1-3 rings of cells with thin radial walls; carpocephala unlobed - 5
5- Capsules surrounded by pendant, white skirt of lanceolate segments...Asterella tenella
5- Capsules lacking white skirt...Mannia (3)
C6 - Thallus lacking any of above unique characteristics.
Plants primarily floating (may be stranded); thallus linear & freely dichotomous; epidermal pores, air chambers & ventral scales usually present...Riccia fluitans
S1 - Thallus with distinct midrib & unistratose wings
1- Thallus small (1-4 mm wide) with hairs on margins only; midrib lacking central strand; gametangia on ventral branches...Metzgeria (4)
1- Thallus larger (3-6 mm wide) lacking hairs; midrib with central strand; gametangia on dorsal surface of midrib...Pallavicinia lyellii
S2 - Thallus with indistinct midrib & multistratose wings thinning to margin; terrestrial & green.
1- Thallus freely branched; rhizoids few or absent...Riccardia (4)
1- Thallus mostly unbranched.
2- Thallus with thick midrib area, red tinged in sunlight...Pellia (3)
2- Thallus lacking distinctive midrib area, but with distinctive greasy luster & feel...Aneura (2)
S3 - Thallus with scalloped or distinctly wavy, irregular margins
1- Thallus margins regularly lobed; flask-like gemmae bottles & Nostoc colonies common...Blasia pusilla
1- Thallus margins irregularly lobed; lacking gemmae bottles & Nostoc colonies...Moerckia (2)
S4 - Thallus narrow with irregular, leaf-like lobes.
1- Thallus erect & fleshy from creeping, rhizome-like base; lobes isophyllous...Haplomitrium hookerii
1- Thallus lacking any of above unique characters; rhizoids usually purplish...Fossombronia (4)
1E Leaves with ciliate lobes to near base or with distinctly ciliate margins -- L1
1D Leaves 3-4 lobed or toothed -- L2
1C Leaves complicate-bilobed (leaves folded into differentiated dorsal & ventral halves).
2 Ventral half larger (appearing succubous); underleaves lacking -- L5
2 Dorsal half larger (appearing incubous).
3 Underleaves readily evident -- L3
3 Underleaves vestigial or lacking -- L4
1B Leaves distinctly bilobed, but not folded (plane with 2 similar lobes).
4 Leaves with sub-transverse to transverse insertion; lower leaves may differ -- L8
4 Leaves with distinctly succubous insertion.
5 Underleaves readily evident -- L6
5 Underleaves vestigial or lacking -- L7
1A Leaves unlobed to emarginate.
6 Leaves with distinctly incubous insertion -- L9
6 Leaves with distinctly succubous insertion.
7 Underleaves readily evident -- L10
7 Underleaves obscured by rhizoids, minute or lacking -- L11
L1 - Leaves with ciliate lobes, margins, or bases
1c- Leaves ciliate to lamina 1-4 cells high, 4-7 lobed & succubous; plants 2-3 pinnate...Trichocolea tomentella
1b- Leaves ciliate to base, 3-4 lobed & transversely inserted.
2- Lobes 7-14 cells long & uniseriate to base; underleaves 7-14 cells long...Blepharostoma trichophyllum
2- Lobes 5-8 cells long & 2 cells broad at base; underleaves 2-3 cells long...Telaranea nematodes
1a- Leaves with ciliate margins.
3- Cilia around entire margin of leaves; shoots 1-2 pinnate; leaves 3-5 lobed with long cilia...Ptilidium cilare/pulcherimum
3- Cilia restricted to leaf bases.
4- Leaves complicate-bilobed; lobule a tongue-shaped lamina (parallel to stem)...Porella austinii/porelloides
4- Leaves with 3-4 shallow, cuspidate lobes; ciliate underleaves...Barbilophozia (7)
L2 - Leaves 3-4 lobed and/or distinctly toothed
1c- Leaves with 3 lobes unequal in size (2 smaller); underleaves lacking...Tritomaria (3)
1b- Leaves with 3-4 lobes of uniform size & shape.
2- Leaf sinuses extending deep into basal half of leaf; leaves 3-4 lobed to near base; branching pinnate...Kurzia (2)
2- Leaf sinuses restricted to apical half of leaf.
3- Leaves incubous.
4- Branching dichotomous; underleaves small; ventral flagella common...Bazzania (3)
4- Branching pinnate; lobes strongly incurved; underleaves similar to leaves...Lepidozia reptans
3- Leaves succubous.
5- Leaves with bases & underleaves ciliate; lobes (4x) cuspidate...Barbilophozia (7)
5- Leaves & underleaves lacking cilia; lobes (3-4x) not cuspidate...Lophozia (18)
1a- Leaves with few to many sharp marginal teeth that may vary in size & shape.
6- Leaves not complicate bilobed; underleaves present; shoots unbranched...Tetralophozia setiformis
6- Leaves complicate-bilobed, smaller lobe on top.
7- Lobes elongate, parallel-sided & directed in strongly different directions from lobules; perianths terete, sharply plicate...Diplophyllum (3)
7- Lobes rotund to ligulate & directed in same direction as lobules; perianths strongly flattened, smooth...Scapania (17)
L3 - Leaves complicate-bilobed; incubous; underleaves large
1- Underleaves unlobed (sinus <1/4 of underleaf length).
2- Lobule a tongue-shaped lamina (parallel to stem)...Porella (2)
2- Lobule inflated pouch (perpendicular to stem) along posterior edge of lobe; underleaves reniform; apical lobular tooth minute to very long...Leucolejeunea (2)
1- Underleaves distinctly bilobed (sinus >1/4 of underleaf length).
3c- Lobule inflated pouch (perpendicular to stem) along posterior edge of lobe; perianths 5-angled; leaves with uniformly rounded apices...Lejeunea (2)
3b- Lobule helmet-like sac (parallel to stem) on stalk; perianths trigonous & flattened.
4- Lobes ending in abrupt short point; stylus lacking; plants on wet rocks; deep, greasy green...Jubula pennsylvanica
4- Lobes rounded; stylus present; on trees & dry rocks; commonly reddish...Frullania (10)
3a- Lobules not inflated (explanate) or reduced to small/minute basal fold (vestigial).
5- Lobules explanate & parallel to stem; on trees & rocks; commonly reddish...Frullania (10)
5- Lobules vestigial; leaves with uniformly rounded apices; underleaves 1-3.5x stem width & not cordate; perianths sharply keeled...Lejeunea (2)
L4 - Complicate-bilobed; incubous; underleaves lacking
1- Plants >1 mm wide; cells smooth; rhizoids on lobules; perianths flat & truncate...Radula (3)
1- Plants <1 mm wide; cells often papillose; rhizoids on stem; perianths 5-angled...Cololejeuna biddlecomiae
L5 - Complicate-bilobed; succubous
1- Lobes elongate, parallel-sided & directed in strongly different directions from lobules; perianths terete, sharply plicate...Diplophyllum (3)
1- Lobes rotund to ligulate & directed in same direction as lobules; perianths strongly flattened, smooth & with truncate mouth...Scapania (17)
L6 - Leaves bilobed & succubous; underleaves clearly evident
1- Underleaves lanceolate.
2- Leaves distinctly bilobed & joined to underleaves...Harpanthus (3)
2- Leaves emarginate & free from underleaves...Nardia insecta
1- Underleaves distinctly bifid.
3- Plants reddish & small (<0.7 mm); leaf lobes unequal in size & rounded ('mittens')...Cladopodiella (2)
3- Plants yellow-green & large (>1 mm); leaf lobes equal in size.
4- Underleaves with lateral teeth; rhizoids restricted; perianth present...Lophocolea (4)
4- Underleaves lacking lateral teeth; rhizoids scattered; marsupium present...Geocalyx graveolens
L7 - Leaves bilobed; succubous; underleaves obscured by rhizoids, minute or lacking; shoots 0.5-1.5 mm wide.
1- Underleaves obscured by abundant, scattered rhizoids; marsupium present...Geocalyx graveolens
1- Underleaves minute or lacking; perianth present.
2- Trigones large to bulging.
3- Leaf insertion oblique throughout; leaves rarely canaliculate...Lophozia (18)
3- Leaf insertion transverse above; leaves commonly canaliculate...Anastrophyllum (4)
2- Trigones lacking.
4- Underleaves minute; leaf lobes unequal in size & rounded ('mittens')...Cladopodiella (2)
4- Underleaves lacking; leaf lobes ~equal in size.
5- Leaves purplish-black with rounded lobes; hyalodermis lacking...Gymnocolea (2)
5- Leaves with connivent lobes; hyalodermis present....Cephalozia (9)
L8 - Leaves bilobed with transverse insertion (Lower leaves may show trend towards succubous insertion)
1- Plants minute (shoots <0.5 mm wide).
2- Leaves glaucous from secreted filaments; isophyllous (underleaves like leaves); alpine...Anthelia juratzkana
2- Leaves lacking any of above characters; branching predominantly intercalary...Cephaloziella (8)
1- Plants small to moderate in size (shoots >0.5 mm wide).
3c- Leaves strongly concave & imbricate; shoots julaceous; underleaves vestigial to lacking; whitish in color...Gymnomitrion (2)
3b- Leaves like "billowing sails" (strongly inflated base with water sac & ciliate lobes)...Nowellia curvifolia
3a- Leaves lacking any of above unique characters; underleaves vestigial to lacking; leaf cells trigonous...Marsupella (5)
L9 - Leaves unlobed & incubous
1- Leaves opaque, yellow-green, pointed & occasionally bidentate...Metacalypogeia schusterana
1- Leaves translucent, gray to blue-green & rounded apically...Calypogeja (8)
L10 - Leaves unlobed & succubous; underleaves clearly evident
1- Underleaves bilobed; purplish pads lacking; sporangia open along longitudinal lines...Chiloscyphus (2)
1- Underleaves lanceolate; leaves orbicular.
2- Rhizoids densely matted; perianths laterally compressed; gemmae often present...Mylia (2)
2- Rhizoids scattered; perianths on fleshy perigynium & plicate; gemmae lacking...Nardia (2)
L11 - Leaves unlobed & succubous; underleaves obscured by rhizoids, minute or lacking
1- Leaves "pleated" (dorsal fold) & decurrent to midline; perianths laterally compressed...Plagiochila (2)
1- Leaves neither "pleated" nor strongly revolute.
2- Leaves longer than broad; rhizoids numerous; perianth smooth with sunken beak...Jungermannia lanceolata
2- Leaves orbicular; perianth not as above.
3- Trigones small, but distinct; perianth distinctly 3-5 keeled with crenulate mouth...Solenostoma (9)
3- Trigones moderate to large & bulging.
4- Ventral flagella abundant; perianth plicate above with denticulate mouth...Odontoschisma (4)
4- Ventral flagella lacking; perianth plicate above with distinctly ciliate mouth...Jamesoniella autumnalis
This key attempts to comprehensively cover New England but may be useful in adjacent States or Provinces. It is adapted, with permission, from "A Perspective Oriented Guide for the Identification of North American Bryophyte Genera" by Malcolm Sargent and Diane Lucas 2012 moss-guide. Any imprecisions or errors are exclusively mine.
Use the 4 line initial key to find the appropriate morphological group further down in the key.
Next read the major statements that start with a letter and are bold in the order presented. Do not skip major statements. If your specimen doesn't fit, go to the next major (lettered bold) statement. Plants that might fall into more than 1 category are listed multiple times in the key.
Lastly, follow the couplets under each major statement as you would any dichotomous key.
Note that when there are more than 2 choices in the major statements or in the initial couplet of the subkeys, they are lettered in descending order. I have found this makes the key a little easier to use and avoids the error of skipping a choice. If there are only 2 choises then the subkey statements are NOT lettered.
The number in parentheses is the number of species reported for New England if there are more than 2. Species are given where only 1 or 2 are known from New England
I have attempted to match the nomenclature in Mary Lincoln's Liverworts of New England since that is the only comprehensive key for this area. This differs from the pending BFNA nomenclature and differs from Raymond E. Stotler and Barbara Crandall-Stotler "A Synopsis of the Liverwort Flora of North America North of Mexico" (29 December 2017) doi.org/10.3417/2016027.
Suggestions, errors or a key you wish to have posted? Email info@DigitalNaturalist.info.
last update 2025-Jun-06