Sub-Guide to Freely Branched (mostly pleurocarpous) Mosses

Group P1 - Shoots strongly flattened (complanate) or angular (Skeleton)

Shoots angular with leaves folded (conduplicate); plants aquatic, submerged part of year

Leaves with a narrow, single costa; SE

Leaves ecostate (costa lacking); leaves keeled or flat; WS

Shoots complanate.

Leaves with a narrow, single costa.

Plants with dimorphic (ventral amphigastria), bordered leaves; FL, BC, AK

Plants prostrate with large lateral leaves and smaller dorsal ones; FL

Plants without both large and small leaves.

Leaf tip rounded-obtuse, leaves asymmetric, upper leaf cells >5:1; WS*

Leaf tip obtuse, leaves undulate, asymmetric; leaf cells 4-7:1; W

Leaf tip truncate, leaves asymmetric, inflexed on one side; FL

Leaf tips acuminate to acute.

Leaf margins coarsely serrate above; leaf tip not twisted; W

Leaf margins distinctly serrulate, leaf tip twisted at apex; E, WA

Leaf margins entire, leaf tip not twisted, in wet swampy places; WS

Leaves with a long, double costa ending above leaf middle.

Leaf cells unipapillose both surfaces, costa ending near leaf apex; FL, LA

Leaf cells smooth, costa about 3/4 of leaf length.

Leaves bordered with linear cells, leaf tip entire or serrulate; FL, LA

Leaves not bordered, leaf acuminate with sharply serrate margins; FL

Leaves with a short & double costa, or none.

Leaf cells large, lax, hexagonal, often rhizoids and papillose gemmae on leaf tips; E, N, CA

Leaf cells firm- to thick-walled, rounded to linear.

Leaves slenderly long decurrent; leaf margins entire, or serrulate at tip; WS

Leaves shortly decurrent, undulate or not; on vertical substrates; WS*

Leaves not decurrent.

Leaves obtuse, asymmetric and with a basal lobe; MS, TN, NC, VA

Leaves secund; very shiny plants; margins sharply serrulate above; WS

Leaves straight or slightly secund at tips.

Rhizoids axillary and papillose; stem hyalodermis well or moderately developed.

Leaves +serrate throughout; alar cells quadrate; WS*

Leaves +entire; alar cells +undifferentiated; WS*

Rhizoids below leaf insertions and smooth; stem hyalodermis lacking.

Leaf apical cells long.

Alar cells enlarged, subquadrate and thick-walled; WS

Alar cells quadrate, but neither particularly enlarged nor thick-walled.

Leaves acuminate; pseudoparaphyllia filamentous; E

Leaves broadly acute; pseudoparaphyllia lacking; WS

Alar cells +undifferentiated; pseudoparaphyllia lacking; WS

Leaf apical cells short; pseudoparaphyllia foliose; E, SW

Leaves with a narrow, single costa.

Leaf margins with cilia, plant stem and branches with paraphyllia; E

Leaf margins serrate and strongly revolute to near apex; alar cells differentiated; W

Leaf margins serrulate; leaves concave -cucullate; leaf tips twisted and apiculate; E

Leaf margins entire or slightly serrulate apically; paraphyllia lacking.

Median leaf cells long.

Branching +pinnate and in one plane; lawns and disturbed areas; WC, NY

Branching irregular; wet soil and rocks; W

Median leaf cells intermediate; stems red; main stems not julaceous; A/A

Median leaf cells short; stems growing singly at right angles to bark; SE

Leaves with costa ~1/2 leaf length & forked; alar cells quadrate & numerous; AK, CO, NM

Leaves with a short, double costa or none.

Leaves serrulate to dentate.

Leaves acute to acuminate; alar cells numerous & strongly differentiated; WC

Leaves rounded-obtuse; alar cells indistinctly subquadrate; WS(N)

Leaves spinulose-serrate to serrulate at the apex.

Leaves spinulose-serrate & hyaline above; shoots julaceous; cells papillose; WS

Leaves entire to slightly serrulate tip; cells smooth.

Shoots curved-ascending (dry); alar cells +undifferentiated; E

Shoots straight (dry); alar cells numerous & quadrate; E

Leaves entire; plants in very wet places, e.g., shallow water; alar cells short and wide; WS*

Stems red; plants +robust and loosely ascending; costa double (long or short) or lacking; WS*

Stems green; plants +slender and creeping; costa long and single, short and double, or lacking; WS*

Group P4 - Plants with erect branches from a creeping stem (Skeleton)

Costa long and single.

Alar cells oblong to linear and extending up leaf margin as a border.

Leaves contorted when dry; leaf cells smooth; FL

Leaves involute when dry, leaf cells often bulging and papillose; GC

Alar cells quadrate to oblate.

Branching pinnate to bipinnate (frondose); costa toothed at back; CA

Branching irregular; costa not toothed; alar cells extending up leaf margin; E

Alar cells +undifferentiated.

Leaves contorted when dry; basal cells uniformly elongate; CP, SA

Leaves channeled at the costa; margins erect or incurved at the apex; E

Leaves often keeled, never channeled; margins plane or reflexed; SA

Costa double with 1 long and 1 short branch; leaves concave or oblong-ovate; ON

Costa variable (single, short and double or lacking within the same plant); on trunks of trees.

Secondary stems sub-pinnately branched; brood bodies lacking; E

Secondary stems unbranched; septate brood bodies often present; GC

Group P5 - Plants with leaves distinctly sickle-shaped and turned to one side (falcate-secund) (Skeleton)

Costa long, single and narrow.

Paraphyllia abundant and filamentous; stem leaves deeply plicate, not complanate; WS

Paraphyllia lacking.

Leaf cells prorulose; leaves plicate and rugose; WS*

Leaf cells smooth.

Stems with a hyalodermis (thin-walled, hyaline cells on stem surface).

Leaves plicate and denticulate in upper portion; WS*

Leaves striolate (finely ridged) to plane and entire to slightly denticulate.

Alar cells inflated; plants occurring in streams on rocks or wet places; WS

Alar cells little differentiated; plants in rich fens; N

Stems lacking a hyalodermis (thick-walled cells on stem surface).

Plants of upland habitats, leaves plicate; WS

Plants of wet habitats, leaves not plicate.

Leaves keeled, 3-ranked; WS*

Leaves neither keeled nor 3-ranked.

Costa excurrent; alar cells abruptly inflated or undifferentiated; WS*

Costa subpercurrent; plants in fens and seeps.

Leaf margins finely denticulate; WS*

Leaf margins entire.

Central strand (small cells) in stem; WS*

Central strand lacking; N

Costa shorter than above; alar cells few and thick -walled; N

Costa short and double, or none.

Arms of double costa not joined at base; AK

Arms of double costa meeting at the base, or none.

Shoots in flat, evenly pinnate, feather -like, fronds; plants large; WS*

Shoots loosely complanate; plants very shiny; leaves very serrulate above; E, NW

Shoots julaceous; found in wet places (often submerged); WS*

Shoots lacking the above unique characters.

Leaf cells prorulose; leaves crowded & secund; alar cells subquadrate; E, AK, BC

Leaf cells smooth.

Alar cells in several rows and thick -walled; leaves serrate above; SE

Alar cells in 1-2 rows with 2-3 cells inflated; leaves +serrulate; E

Alar cells in triangular patches; leaves +entire.

Plants on wet rocks in mountain streams; branching +irregular; WS

Plants of mesic to wet habitats; branching regularly pinnate; WS

Group P6 - Plants with paraphyllia or tomentum on stem (Skeleton)

Stems with tomentum, calciphile in fens, swamps; WS*

Stems with paraphyllia.

Leaves with a short, double costa or none; plants irregularly pinnate.

Leaves rugose and falcate -secund; NW, WA, OR

Leaves smooth, straight and imbricate when dry; costa variable; WC

Leaves with a long, double costa; stems red.

Plants 2-3 -pinnate with stepwise flat fronds; upper leaf cells prorulose; WS*

Plants irregularly to 1-2 -pinnate; cells smooth or prorulose.

Leaves spinulose -serrate all around; NE, N

Leaves serrate in upper half; stem leaves rugose at acumen base; E

Leaves with a long, narrow costa.

Plants dendroid or plumose; upper leaf cells short (2-5:1).

Plants strongly curled dry, leaf margins serrate at tip; on trees primarily; WC, ID

Plants little altered dry; leaf margins strongly serrate in upper half; on rich soil; E

Plants curled dry, leaf margins serrate at tip; on trees primarily; NW, ID

Plants irregular pinnate; cells linear (> 8:1); margins spinulose; NE, N

Plants complanate; stem leaves undulate; W

Plants lacking the above unique characters.

Alar cells inflated in well marked groups.

Stem leaves deeply plicate; paraphyllia filamentous and abundant; soil and rocks; WS

Stem leaves plane; paraphyllia foliose and few to many; wet areas; WS*

Alar cells mostly not differentiated, if so, not inflated.

Paraphyllia cells distinctly papillose over the lumen; paraphyllial margins

often denticulate/serrulate.

Plants small; stem leaves <0.6mm; leaf cells minutely pleuripapillose.

Leaf cells pleuripapillose both sides of leaf; E

Leaf cells pleuripapillose back side of leaf only; E, AZ

Plants larger; stem leaves 1-1.9 mm; branch leaf cells mostly unipapillose.

Plants 1-pinnate, suberect and wiry; WS

Plants 2-3-pinnate, mostly spreading and softer; E, NW

Paraphyllial cells smooth or indistinctly ornamented; paraphyllial margins often

denticulate/serrulate or ciliate.

Leaf cells with either forked, or elongate & curved papillae; leaves ovate; E

Leaf cells either prorulose or with short & simple papillae; leaves +lanceolate.

Plants 2-3 pinnate & large; stem leaves 1-1.9 mm; E, NW

Plants regularly 1-pinnate; stem & branch leaves somewhat differentiated;

E, AZ, NM

Plants irregularly branched; stem and branch leaves uniform.

Leaf cells elongate, oblong-rhombic to oblong-linear.

Paraphyllia linear-lanceolate and numerous.

Laminal cells papillose or prorulose;

capsules inclined & asymmetric; W

Laminal cells +prorulose; capsules erect & symmtric; N*

Paraphyllia filiform; capsules inclined to horizontal and curved; WS*

Leaf cells short (isodiametric or nearly so, hexagonal to short-rhombic); W

Leaf cells smooth or indistinctly ornamented.

Leaf bases ciliate; WS*

Leaf bases lacking cilia; W

Group P7 - Plants with red stems (Skeleton)

Costa long and double.

Stems with paraphyllia.

Plants dendroid (tree-like) on soil in wet, shady places; E

Plants 1-3 -pinnate with arched, ascending stems.

Plants with stepwise flat fronds; upper leaf cells prorulose; WS(N)

Plants lacking stepwise flat fronds; leaf cells smooth; WS(N)

Plants irregularly branched; stem leaves rugose at acumen base; E

Stems without paraphyllia and irregularly branched; leaves plicate; WS*

Costa long and single.

Plants frondose; branches circinate when dry; paraphyllia abundant; cells prorulose; WC, ID

Plants not frondose; cells smooth.

Stems with abundant, filiform & branched paraphyllia; WS(N)

Stems lacking paraphyllia.

Leaf margins +revolute throughout; alar cells oval to transversely elongate; W, NL

Leaf margins plane; alar cells +undifferentiated; A/A

Costa short and double, or none.

Leaves distinctly falcate -secund; WS

Leaves squarrose to squarrose -recurved; WS*

Leaves straight.

Leaves with a hyaline tip; shoots whitish and +julaceous when dry; cells papillose; WS

Leaves with a green tip; leaf cells smooth.

Alar cells inflated, hyaline and thin -walled in distinct auricles; WS (N)

Alar cells short -oblong with thick orange walls; WS

Group P8 - Plants with shoots flat on top and appearing "braided" (Skeleton)

Costa single and narrow; pseudoparaphyllia present.

Cells prorulose on leaf back; regularly 1-pinnate; leaves serrulate all around; E, AK, BC

Cells smooth; closely 1-pinnate in feather -like fronds; leaf tips serrulate; WS*

Costa short and double, or none; pseudoparaphyllia usually present.

Alar cells in transverse rows and inflated; leaves sharply serrulate above; E, BC, WA

Alar cells in triangular areas, inflated or not; leaves entire to serrulate; WS

Group P9 - Leaves undulate or rugose (irregular undulations) (Skeleton)

Leaves with double costa of intermediate length; leaves plicate below, rugose above; on soil; NW

Leaves with a narrow, single costa.

Leaves undulate and asymmetric; shoots complanate; paraphyllia on stems; W

Leaves rugose; shoots round; paraphyllia lacking.

Leaf cells prorulose; WS*

Leaf cells smooth; leaves stoutly apiculate; CP, SA

Leaves with a short, double costa or none.

Plants julaceous and growing in wet (submerged) areas; WS

Plants not julaceous; leaves complanate and undulate; on rocks or trees; WS*

Group P10 - Leaves dimorphic (two forms on the same axis) (Skeleton)

Smaller leaves (amphigastria) on the ventral (lower) side of stem in a single row; FL, BC, AK

Smaller leaves on the dorsal (upper) side of the stem in double rows; FL

Group P11 - Leaves with awns, hair-points or hyaline apices (Skeleton)

Leaves with a narrow, single costa.

Leaf cells papillose; leaves catenulate; costa pellucid; W, AK

Leaf cells smooth; leaves not catenulate; costa opaque.

Cell walls sinuose/nodulose throughout; WS

Cell walls strongly pitted, especially at bases & apices of leaves; NW

Cell walls straight & smooth.

Leaf apex flat, filiform and serrate; leaves abruptly acuminate; N* (S to NC)

Leaf apex a long, flexuose tip, leaves concave and shiny; pendulous FL

Leaves with a short, double costa or none; apex hyaline or abruptly contracted to long setaceous point

Leaf cells papillose; leaf apex hyaline

Leaf cells unipapillose on both sides; WC

Leaf cells with 1 or more, simple to forked papillae; WS

Leaf cells with many, low, rounded papillae and very thick walls; AZ, TX

Leaf cells smooth, leaf apex hyaline or yellow

Leaf apex yellow; alar cells inflated and hyaline; BC

Leaf apex hyaline; alar cells undifferentiated; leaves appressed; NW, OR

Group P12 - Plants thread-like (leaves <1mm) (Skeleton)

Leaves to 1 mm; costa variable; cells rounded -elliptic; pseudoparaphyllia lanceolate; N,W

Leaves 0.5-0.8 mm; costa none or short and double; cells rhombic; paraphyllia few; WS*

Leaves 0.15-0.5 mm; costa none or short and double; cells rhombic; paraphyllia none; WS

Note - see Group 20 also for several of these mosses where costa form is variable within a single plant.

Costa >2/3 the leaf length with branches of +equal length.

Leaf cells unipapillose on both surfaces; FL, LA

Leaf cells smooth; plants in flat mats; secondary stems prostrate.

Marginal cells linear in a single row; costa ends near apex; FL, LA

Marginal cells little differentiated; costa ~2/3 of leaf length; LA, MS

Costa 1/3-2/3 the leaf length with branches of +equal length.

Leaf cells prorulose.

Stems red.

Plants regularly 2-3 -pinnate with stepwise flat fronds; WS*

Plants irregularly branched; leaves plicate with broad flat tip; WS*

Stems green; plants loosely pinnate; leaves decurrent; costa variable; WS(N)

Leaf cells smooth.

Paraphyllia abundant.

Leaves spinulose-serrate all around & decurrent; WS(N)

Leaves serrate in upper half; leaves not decurrent; E

Paraphyllia often few and inconspicuous; leaves decurrent and dimorphic; W

Paraphyllia lacking.

Leaves serrate above; secondary stems erect -ascending; FL

Leaves entire to somewhat serrulate; costa often variable.

Leaves slenderly long decurrent; costa branches often unequal; WS

Leaves not distinctly decurrent.

Alar cells subquadrate and slightly porose; in rich, open fens; N

Alar cells quadrate or inflated; on rocks in mountain streams; WS

Alar cells thick walled, porose; plants irregularly branched; AK

Group P14 - Costa single and narrow; leaves with distinct decurrencies (Skeleton)

Leaf cells pleuripapillose; decurrencies broad to auriculate.

Costa +subpercurrent; leaf margins crenulate from projecting papillae; N*

Costa to mid -leaf (forked/shorter); leaf margins serrulate; leaves dimorphic; W,SE

Leaf cells distinctly prorulose; E

Leaf cells smooth or indistinctly ornamented.

Plants large and dendroid; leaf tips rounded and sometimes apiculate; NW

Plants arching and +regularly pinnate; leaf apical cells shorter than medial cells; W

Plants neither dendroid, arching-pinnate, nor complanate; apical cells similar in size to medial cells.

Leaves minutely prorulose with twisted apices; cells 3 -4:1; E

Leaves smooth with plane or twisted apices; cells mostly >4:1.

Plants on rocks in or along cold streams; costae variable from leaf to leaf; WS

Plants on soil in drier habitats; costae not variable; WS

Group P15 - Costa single and narrow; leaves with a distinct marginal border (Skeleton)

Leaves bordered with cilia.

Cilia from leaf base to apex; paraphyllia polymorphous, lacinate, ciliate, and few to abundant; E

Cilia at leaf base only; paraphyllia filiform and abundant; WS*

Leaves bordered with linear cells.

Leaf margins serrulate to serrate.

Shoots complanate; leaves dimorphic (ventral amphigastria); FL, BC, AK

Shoots angular; leaves conduplicate; plants submerged part of year; SE

Shoots round; leaves plane with multistratose borders.

Leaves +lanceolate and acuminate with serrate, unistratose marginal cells; OR

Leaves +ovate and acute with serrulate marginal cells; E

Leaf margins entire; on rocks and tree trunks.

Border extends to near leaf apex; cells intermediate in length; BC, CA

Border extends to near mid -leaf; cells short; cladocarpous; FL

Group P16 - Costa single and narrow; leaves with distinct alar cells (Skeleton)

Alar cells enlarged or inflated; hyaline, or yellow.

Paraphyllia present.

Stem leaves plicate; paraphyllia filamentous and abundant; WS

Stem leaves plane; paraphyllia foliose and either abundant or few; WS*

Paraphyllia lacking.

Leaves broadly rounded at tip.

Leaves with an apiculus; plants reddish; A/A

Leaves without an apiculus; alar cells thin-walled; in fens and swamps; N

Leaves acuminate or bluntly acute.

Leaves falcate -second.

In fens or other nutrient rich waters.

Alar cells numerous in large conspicuous groups; WS*

Alar cells few in triangular areas, rectangular and slightly inflated; N

On rocks in or along streams; alar cells subquadrate to oblong; WS

Leaves straight.

Leaves narrowed to long, channeled acumen; WS*

Leaves ovate-lanceolate and narrowed to an acumen; WS*

Leaves acuminate; alar cells often in broad decurrencies; WS

Alar cells small and subquadrate.

Leaves +broadly oblong-ovate.

Shoots +julaceous.

Leaves abruptly apiculate; plants erect; in lawns and gardens; WC, NY

Leaves rounded to acute; plants prostrate; on rocks in or along streams; WS

Shoots +complanate; costa stout; large patch of alar cells; SC, GC

Shoots neither julaceous nor complanate; creeping stems and erect branches; E

Leaves ovate to ovate-lanceolate.

Leaf margins distinctly serrate above.

Branching pinnate to bipinnate (frondose); medial cells <2:1 (+isodiametric); CA

Branching irregular to sub-pinnate; medial cells >2:1; WS(WC, SA)

Leaf margins entire to serrulate.

Leaf cells distinctly papillose; leaf acumen pale; WS(E)

Leaf cells distinctly prorulose; leaves falcate, plicate & rugose; WS*

Leaf cells +smooth; leaf apices green.

Shoots +julaceous (dry); costa stout.

Costa >1/2 leaf length & not forked; TX, NM

Costa 1/3-1/2 leaf length & forked; AK, CO, NM

Shoots not julaceous.

Costa subpercurrent (>2/3 leaf length).

Paraphyllia common; stems & costa +orange; cells +prorulose; N*

Paraphyllia lacking; stems & costa green; cells smooth.

Leaves recurved below & serrulate above; brood bodies lacking; N, W

Leaves plane below & entire above; brood branchlets common; WS

Costa 1/3-2/3 the leaf length.

Alar cells in numerous rows; on bark primarily; SE, OH

Alar cells in a few rows; on rock primarily; N, W

Leaves +lanceolate; shoots not julaceous; plants prostrate.

Leaves on +complanate shoot; costa stout; large patch of alar cells; SC, GC

Leaves plicate and coarsely serrate; upper leaf cells thick -walled; SA, TX

Leaves narrowed to long, channeled acumen and +squarrose -recurved; WS*

Leaves and cells lacking any of the above unique characters.

Alar cells asymmetrically grouped (more on one side of costa,); FL

Alar cells symmetrically arranged; WS

Group P17 - Costa short and double, or none; leaves with distinct decurrencies (Skeleton)

Leaf cells 1-4 papillose; costa variable, usually single/forked; leaves dimorphic; W, SE

Leaf cells smooth; costa short and double, or about 1/2 leaf length

Leaf margins serrulate to serrate all around; alar cells abruptly inflated; WS*

Leaf margins entire or with serrulate tips.

Plants on rocks in or along cold streams; costae variable from leaf to leaf; WS

Plants on soil in drier habitats; costae not variable.

Alar cells abruptly inflated; AK

Alar cells poorly differentiated; WS

Group P18 - Costa short and double, or none; leaves with a distinct marginal border (Skeleton)

Leaves bordered with cilia; paraphyllia few to abundant (costa usually single); E

Leaves bordered with linear cells from base to mid-leaf; margins entire; on rocks or trees; FL

Group P19 - Costa short and double, or none; leaves with distinct alar cells Skeleton)

Alar cells inflated and hyaline, or yellow.

Leaves distinctly falcate-secund.

Plants regularly pinnate, feather like; flat oblong, triangular fronds; WS*

Plants irregularly pinnate to unbranched.

Plants in calcareous wet areas; leaves concave and apiculate; WS*

Plants on rocks in mountain streams or wet places; leaves ovate and concave; WS

Plants in other habitats.

Stems with a hyalodermis; alar cells in large, almost decurrent areas; WS

Stems lacking a hyalodermis; leaf apices serrate to serrulate.

Alar cells subquadrate and in +triangular group; apices serrate; SE

Alar cells oblong and in +triangular group; apices serrulate; E, NW

Alar cells oblong and in rows 1(-2) cells wide; apices +entire; E

Alar cells few with short-oblong cells above; apices serrulate; WS

Leaves homomallous; alar cells abruptly and strongly inflated as "bubble " cells; E

Leaves neither falcate-secund nor homomallous.

Stem leaves contracted to a long, yellow, setaceous point; BC

Stem leaves without a setaceous point, acute, acuminate or apiculate.

Leaves squarrose-recurved; alar cells oblong and +inflated; WS*

Leaves erect to spreading; alar cells hyaline.

Plants erect; stems with a hyalodermis; alar cells in auricles; WS

Plants prostrate; alar cells not in auricles.

Cells at leaf insertion enlarged in 1 or 2 distinctive rows.

Alar cells rounded to the insertion; on rotten logs; FL

Alar cells not rounded to the insertion.

Alar cells strongly inflated as "bubble" cells; setae ~3 cm; E

Alar cells somewhat inflated; setae ~3 mm; epiphytic; FL

Cells at leaf insertion not in a distinctive row; leaves >1mm.

Leaves serrulate throughout and decurrent; alar cells thin -walled; WS*

Leaves entire, not decurrent. alar cells thick -walled; WS

Alar cells quadrate to short oblong.

Leaves distinctly secund, or falcate-secund; leaf cells smooth.

Leaves ovate and concave; plants of wet places and in mountain streams; WS

Leaves lacking any of the above unique characters.

Costa to ca. 1/3 the leaf length with the 2 branches separate at the base; AK

Costa shorter with branches joining at the base; pseudoparaphyllia common; WS

Leaves straight.

Leaves wide-spreading to squarrose-recurved and with a long, channeled acumen; WS*

Leaves flattened into one plane, i.e., shoots complanate.

Leaves serrulate throughout; stem hyalodermis present; WS*

Leaves serrulate in upper half; stem hyalodermis lacking; E

Leaves entire except at apex; alar cells numerous; WS (not WC)

Leaves +concave and imbricate, i.e., shoots +julaceous.

Branches strongly curved when dry; numerous alar cells extending up leaf margins; E, AZ

Branches +straight when dry; alar cells otherwise.

Stems red; alar cell walls thick and orange; WS

Stems green; alar cell walls thin and colorless; SE

Leaves lacking any of the above unique characters.

Branches strongly curved when dry; straight when moist.

Leaf cells >5:1; 5-20 quadrate alar cells at the basal angles; WS*

Leaf cells ~3:1; numerous oblate alar cells extending up leaf margins; E, AZ

Branches loosely curled when dry.

Stems with numerous paraphyllia; WC

Stems lacking paraphyllia.

Capsules +erect & symmetric; upper leaf cells narrowly rhomboidal.

Leaf margins reflexed below; brood branchlets common; WS*

Leaf margins planar below; brood branchlets lacking; WS*

Capsules +inclined & asymmetric; upper leaf cells shortly oblong-rhomboidal; WS*

Branches +straight when dry.

Leaves <1 mm.

Leaves catenulate; cells smooth; N, W

Leaves strongly appressed; cells minutely pleuripapillose; AK, CO, NM

Leaves >1 mm.

Leaf cells prorulose; alar cells transversely elongate; WC

Leaf cells smooth.

Alar cells extending up the margins for <1/6 of leaf length.

Leaves acuminate.

Stem leaves serrulate throughout; WS*

Stem leaves entire and somewhat decurrent; WC

Leaves mostly obtuse to acute; WS (not WC)

Alar cells extending up margin for >1/6. leaf length; E

Plants tufted from vertical surfaces; capsules +immersed; E

Plants in mats on horizontal surfaces; capsules exserted; WS*

Group P20 - Costa of uncommon or variable form (Skeleton)

Costa of uncommon form.

Costa long, wide and with lateral spurs; leaves with multistratose streaks; TX

Costa single with several minor basal, supplementary costae; stems red; W, NL

Costa single with a forked tip (Y-shaped); CO, AK

Costa variable on same plant (single or double or variations of these in different leaves).

Costa usually variable (double, double with a long branch, Y-shaped, single, forked or short and double).

Found on rocks or wet places in mountain streams; WS

Found on trees near coast; plants with many paraphyllia; WC

Costa mostly double (1/3-2/3 leaf length), but sometimes single or short and double.

Stems loosely pinnate; leaves dimorphic and decurrent; on soil, rock and trees; WS(N)

Stems scarcely branched; leaves neither dimorphic nor decurrent; fens; N

Costa mostly double with one long branch (to 1/3 leaf length) and one short branch, but

occasionally single or short and double; ON

Costa mostly single within the genus or the given species.

Costa rarely to often forked (with or without a spine), Y-shaped or with lateral spurs.

Plants large and +robust; stem leaves typically >2 mm.

Leaves serrulate to near base with short and broad apical cells; WS

Leaves entire, broad, concave and with apical cells similar to medial cells.

Leaves abruptly apiculate (reflexed); weedy habitats; WC, NY

Leaves rounded to bluntly acute; plants of fens and swamps; N

Plants medium in size; stem leaves typically 1-2 mm.

Leaf margins strongly serrate; alar cells distinct and quadrate; E, WC

Leaf margins entire; costa occasionally Y-shaped; in bogs; WS*

Plants small and slender; stem leaves <1 mm; W, SE

Costa occasionally to frequently short and double.

Leaf margins ciliate; E

Leaf margins serrulate; leaves decurrent; W, SE

Leaf margins +entire; secondary stems sub-pinnately branched; E

Costa mostly short and double within the genus or the given species.

Costa often double with one or both branches to 1/2 leaf length.

Leaves decurrent; leaf margins mostly entire; WS

Leaves not decurrent.

Leaf margins serrulate to dentate; branches terete (round); E

Leaf margins serrulate above; branches complanate; E, SW

Costa occasionally to often single.

Plants with erect branches from creeping stems; septate brood bodies; GC

Plants thread-like; leaves to 1 mm; N, W

Reminder - Definitions for cell length to breadth ratios are found in the Introduction, the Overview and at the end of this section.

Note - only the genera in normal type (NOT in brackets) in the Skeleton to Freely Branched Mosses are included in the following Groups. An expanded explanation of the difference between "Distinct" and "Indistinct" surface ornamentation is found in the Introduction.

Group P21 - Cells long (>8:1), distinctly papillose or prorulose (Skeleton)

Leaf cells papillose; WS*

Leaf cells prorulose.

Shoots curved-ascending (dry); leaves plicate, but not decurrent; W

Shoots straight (dry); leaves smooth & decurrent; E, AK

Group P22 - Cells long, smooth or indistinctly ornamented ^#;
costa single (long and narrow) (Skeleton)

Shoots curved-ascending when dry; leaves plicate; WS, NL

Shoots julaceous; leaves obtuse or acute; plants in or near streams; W

Shoots complanate.

Leaves serrulate throughout with twisted tips; in mesic habitats; WS*

Leaves entire and wide spreading.

Leaves crowded; alar cells numerous and quadrate; FL

Leaves distant; alar cells few and short-to-long rectangular; WS

Shoots triangular; leaves keeled, 3-ranked and slenderly acuminate; in wet places; WS*

Shoots lacking any of the above unique characteristics.

Plants large and +pinnately branched; basal cells porose.

Shoots +erect; leaves deeply plicate; W

Shoots prostrate to arching; leaves plane; W

Plants with irregular branching; leaves spreading and +lanceolate.

Cells at branch leaf apex much shorter than median cells; costa often ending in spine.

Plants aquatic (on rocks in flowing water); branch leaves 1.2 mm or longer; WS

Plants on moist humic soil; branch leaves <1.2 mm; WS

Cells at apex similar to medial cells; costal spine or tooth present or absent.

Costa distinct; brood bodies lacking; WS

Costa indistinct at mid-leaf; gemmae or rhizoids often at back of costa; WS

Plants small, on tree trunks; leaves serrulate and +homomallous; E

^# Note - cells indistinctly papillose, i.e., low papillae, or prorulose.

Group P23 - Cells long, smooth or indistinctly ornamented ^#;
costa double (long or short) or none (Skeleton)

Leaves with a long, double costa; E

Leaves with a short, double costa or none.

Plants aquatic, submerged part of year; cells not porose; leaves keeled or flat; WS

Plants not aquatic.

Rhizoids papillose; stem hyalodermis well or moderately developed.

Alar cells inflated or quadrate; leaves +serrate throughout; WS*

Alar cells +undifferentiated; leaves entire; WS*

Rhizoids smooth; stem hyalodermis lacking.

Leaf apical cells shorter than medial cells; pseudoparaphyllia foliose; E, SW

Leaf apical cells similar to medial cells in length..

Alar cells quadrate; pseudoparaphyllia filamentous; E

Alar cells +undifferentiated; pseudoparaphyllia lacking.

Leaves complanate and serrate above; brood bodies often present; WS

Leaves neither complanate nor serrate; cells mostly porose throughout; A/A

Group 24 - Cells intermediate (3-8:1), distinctly papillose or porulose (Skeleton)

Leaf cells papillose.

Cells pleuripapillose; papillae in a single row over the cell lumen.

Costa single and narrow; papillae simple, on both surfaces of leaves.

Leaves +ovate, +plicate and from a chordate, +auriculate base; FL, LA

Leaves narrowly lanceolate and not auriculate; festoons on twigs and branches; GC

Costa lacking; papillae simple or forked, on upper surface only; E, SW

Cells unipapillose; axillary, filiforme, septate brood bodies often present; FL

Leaf cells prorulose.

Costa long and single.

Paraphyllia abundant; on rocks in mountains; W

Paraphyllia lacking; short, axillary, spindle-shaped brood bodies; FL to LA

Costa short and double; plants small and creeping.

Plants dull; axillary brood bodies present; cells thick -walled; WS*

Plants shiny; brood bodies lacking; cells thin -walled; NC, TN

Group P25 - Cells intermediate, smooth or indistinctly ornamented ^#;
costa single and narrow (Skeleton)

Leaves +falcate to falcate-secund.

Leaves keeled, 3-ranked, slenderly acuminate; plants periodically submerged; WS*

Leaves plicate; plants of upland habitats.

Stems & costa +orange; branch leaf cells +prorulose distally; paraphyllia common; N*

Stems & costa green; branch leaf cells smooth; paraphyllia lacking; WS

Leaves straight.

Plants on tree trunks.

Plants of medium size.

Short, axillary, spindle-shaped brood bodies; FL to LA

Long, axillary, filiform brood branchlets; FL.

Plants small to very small.

Leaves with serrulate margins and long-acuminate apices; branches +julaceous; WS

Leaves with entire margins and gradually acuminate apices; E

Plants on rocks or soil in mesic to wet habitats.

Plants with julaceous shoots; leaves broadly ovate and concave.

Stems red; main stems not julaceous; leaf margins +revolute throughout; W, NL

Stems green; leaf margins plane or recurved below.

Median leaf cells >8:1; AK

Median leaf cells <8:1; W

Plants not julaceous.

Leaves broadly oblong to ovate, concave and with rounded to cucullate apices.

Plants reddish; stem tips cuspidate; leaf tips often apiculate; A/A

Plants green; stems +julaceous; costa often with spines; W

Leaves ovate lanceolate, +plane and with mostly acuminate apices.

Apical cells much shorter than median cells; costa ending in a spine; WS

Apical cells similar to medial cells in length.

Costa percurrent to excurrent.

Costa very wide (75-140µ); leaf margins +entire; WS

Costa narrow (<35µ); leaf margins serrulate to serrate above.

Stems & costa +orange; leaf cells +prorulose; paraphyllia common; N*

Stems & costa green; leaf cells smooth; paraphyllia lacking; WS

Costa 1/2 to 3/4 leaf length.

Leaf margins serrulate above to throughout.

Cells 3-5:1; capsules +cylindric and yellowish; WS

Cells >5:1; capsules +oblong-ovoid and reddish; WS

Leaf margins +entire.

Leaves +wide-spreading; capsules +cylindric and yellowish; WS

Leaves +erect; capsules +oblong-ovoid and reddish; WS

Plants +erect on forest litter, large and pinnately branched; leaves deeply plicate; W

^# Note - cells indistinctly papillose, i.e., low papillae, or prorulose.

Group P26 - Cells intermediate (3-8:1), smooth or indistinctly ornamented ^#;
costa short and double or none (Skeleton)

Plants growing in aquatic habitats.

Plants trailing from a single attachment point in flowing water; leaves keeled or flat; WS

Plants not trailing from a single attachment point.

Plants large and sparsely branched; foliose pseudoparaphyllia; in fens; N

Plants medium and freely branched; cells lax, translucent and empty looking; FL

Plants growing in terrestrial habitats; plants small to medium in size.

Leaves dimorphic (stem vs. branch) and decurrent; costa 1/3 -1/2 leaf length; W

Leaves +homomallous; alar cells abruptly and strongly inflated; on rotten logs; FL

Leaves of stem straight, with a long setaceous point; on trees; NW, OR

Leaves striate to plicate; leaf cells porose throughout; paraphyllia foliose if present; A/A

Leaves obtuse, symmetric and incurved at base on one side only; NC, SC

Group P27 - Cells short (<3:1) and distinctly papillose or prorulose (Skeleton)

Leaf cells pleuripapillose (2-5 papillae per cell).

Leaves fragile above a short ovate base, appressed (dry) and spreading (wet); E

Leaves not fragile.

Cells nodulose (wavy) throughout the leaf; WS

Cells thick -walled and porose; plants coarse and forming large mats; rocks; AZ, TX

Cells neither nodulose nor porose.

Leaf margins papillose-crenulate; basal, interior cells pellucid; E

Leaf margins entire to serrulate throughout.

Stems papillose; leaves not catenulate; costa opaque & variable; W, SE

Stems smooth; leaves catenulate; costa pellucid & uniform; W, AK

Leaf cells strictly unipapillose.

Leaves appressed (dry), squarrose (wet), +lanceolate and with a pale acumen; WS(E)

Leaves not squarrose (wet).

Costa long and single.

Leaf margins serrulate to serrate throughout; costa pellucid; leaves catenulate; W, AK

Leaf margins entire to subserrulate above; costa opaque and often flexuose above.

Stems regularly 1-pinnate with scarce to abundant paraphyllia; E, AZ, NM

Stems irregularly branched.

Paraphyllia present; alar cells +quadrate in small to large groups; W

Paraphyllia scarce to lacking; alar cells +undifferentiated E, OR

Costa short and double or none; leaf margins dentate to spinulose-dentate; E

Leaf cells prorulose at back, especially at upper ends of leaves.

Leaves strongly dimorphic (stem and branch leaves dissimilar); WS(N)

Leaves not dimorphic.

Branches julaceous; leaves rounded -ovate and obtuse; WS(N)

Branches terete; leaves ovate-lanceolate and acuminate.

Costa long & single; W

Costa lacking; E

Group P28 - Cells short (<3:1) and smooth or indistinctly ornamented# (Skeleton)

Costa long and single.

Shoots usually with dense clusters of axillary brood branchlets; often on bark; WS

Shoots julaceous when dry; leaves wide spreading wet.

Stems freely branched; leaves +acute; capsules exserted; NM, TX

Stems sparsely branched; leaves +obtuse; capsules immersed; SE

Shoots +complanate; costa single and stout; large patch of quadrate alar cells; SC, GC

Shoots neither julaceous nor complanate.

Leaf apices rounded -obtuse; cells oval; calcareous areas on bark, rocks; CO

Leaf apices acute to acuminate.

Leaf cell walls strongly sinuose/nodulose throughout; WS

Cell walls strongly pitted, especially at bases & apices of leaves; NW

Leaf cell walls straight.

Upper leaf cells >2:1; basal cells at insertion usually enlarged and yellowish.

Costa >35µ at base; yellowish cells usually in 2-3 rows; WS

Costa <35µ at base; yellowish cells usually in a single row; WS

Upper leaf cells 1-2:1.

Costa subpercurrent (>2/3 the leaf length).

Costa strongly flexuose above; leaves coarsely serrate above; S

Costa stout and toothed at back; leaves serrate above; shoots +bipinnate; CA

Costa +straight; leaves +entire.

Cells +papillose; alar cells +undifferentiated; paraphyllia sparse; E, OR

Cells smooth; alar cells +quadrate/oblate; paraphyllia lacking; N, W

Costa 1/3- 2/3 the leaf length.

Leaf apex obliquely asymmetric; on periodically flooded bark; NW, NB

Leaf apex symmetric and acute to acuminate; alar cells +quadrate/oblate.

Alar cells in numerous rows; on bark primarily; SE, OH

Alar cells in a few rows; on rock primarily; N, W

Costa <1/3 the leaf length, variable & commonly forked; N, W

Costa short and double or none.

Shoot +julaceous; leaves ovate with an apiculus; arctic-alpine; NW

Shoots usually +complanate; leaves +acuminate; cells lax and translucent; FL

Shoots neither julaceous nor complanate; stem leaves with a setaceous point; NW

^# Note - cells indistinctly papillose, i.e., low papillae, or prorulose.

Cells = medial, laminal cells; cells ~2/3 of the way from insertion to apex, midway between the costa and the margin.

Cell length to breadth ratio:

Long cells: >8:1; commonly termed linear or linear-flexuose.

Intermediate cells: 3-8:1; commonly termed elongated, oblong-rhomboidal, fusiform, or elliptical.

Short cells: <3:1; commonly termed isodiametric, quadrate, rounded-quadrate, or rhombic.