1	"Median leaf cells at least in part more than 50 µm broad; margin strongly differentiated"	"Roellia roellii"
1	"Median leaf cells more narrow"	2
2	"Leaf cells echlorophyllose in distal 1/2, the leafy plant thus appearing silvery to whitish; plant of ruderal habitats, or on thin soil over rocks"	3
2	"Leaves and plant not so whitish"	5
3	"Costa excurrent; plant of thin soil in frequently drying sites"	"Bryum lanatum"
3	"Costa percurrent to subpercurrent; plant of various sites, often ruderal"	4
4	"Plants with a reddish blush on the older portions of the stems; neck of capsule as long as urn; plant of thin soil in deep recesses of rock outcrops in alpine and subalpine areas"	"Plagiobryum zierii"
4	"Plants whitish or greenish to base; neck of capsule short; plant of disturbed soil and cracks in rocks, sometimes on highly nitrogenous soil such as that below bird roosts"	"Bryum argenteum"
5	"Leaves with a strong limbidium that is bistratose at least in the basal 1/3"	6
5	"Leaves with limbidium strong to weak or absent, consistently unistratose"	13
6	"Leaves almost orbicular but so strongly distorted when dry as to obscure that character; leaf apex bluntly obtuse with costa ending before the apex"	"Bryum cyclophyllum"
6	"Leaves ovate to lanceolate with acute apices; costa mostly percurrent to excurrent"	7
7	"Leaves ovate to ovate-lanceolate, decurrent with the decurrency extending to the insertion of the next leaf; distal leaf margin minutely serrulate to entire"	"Bryum weigelii"
7	"Leaves not so strongly decurrent"	8
8	"Most median leaf cells 25-40 µm wide; leaves broadest near middle, about 2.5:1, not contorted when dry; plants mostly with a pinkish wash; peristome with cilia fully developed;"	"Bryum schleicheri"
8	"Most median leaf cells less than 30 µm wide; leaf shape various but mostly more narrow, at least somewhat contorted when dry; plants variously colored; peristome with cilia absent or present"	9
9	"Leaves about 2.5:1; leaf margins plane throughout; capsules turbinate, less than 2:1"	"Bryum turbinatum"
9	"Leaves mostly 3:1 or greater; margins recurved at least near base; capsules more elongate"	10
10	"Cells of leaf base not reddened; costae not reddened in 10% KOH; plant synoicous"	"Bryum arcticum"
10	"Cells of leaf base away from the costa reddened; costa and stem very deeply reddened in KOH; plant not synoicous"	11
11	"Peristome with cilia reduced or absent; spores mostly more than 25 µm in diameter"	"Bryum uliginosum"
11	"Peristome with cilia fully developed; spores mostly less than 25 µm in diameter"	12
12	"Some capsules in excess of 5 mm long, somewhat curved at the well-defined neck; median exothecial cells elongate, 3-4:1; spores 14-20 µm in diameter"	"Bryum meesioides"
12	"Capsules mostly about 3 mm long; median exothecial cells quadrate to short rectangular; spores 20-30 µm in diameter"	"Bryum pallens"
13	"Leafy stems with concave leaves closely overlapping without significant reflexing of apices, thus with an overall julaceous appearance"	14
13	"Leafy stems not julaceous"	16
14	"Stem heavily fluted in cross-section; leaves longer than 2 mm, heavily reddened throughout; cells of leaf base somewhat inflated"	"Bryum miniatum"
14	"Stem not fluted in cross-section; leaves smaller, typically reddened only near base; cells on leaf base not inflated"	15
15	"Cells of distal lamina 2-3:1, leaf apices broadly acute on distal portions of the very short stem but almost truncate or cucullate on lower portions of stem"	"Bryum calobryoides"
15	"Cells of distal lamina mostly more than 4:1; leaf apices acute to acuminate, not at all cucullate"	"Bryum blindii"
16	"Basal leaf cells quadrate or nearly so across the width of the leaves, obviously set off from the hexagonal to rhomboidal cells of the median and distal portions of the leaf"	17
16	"Basal leaf cells rectangular with parallel walls, gradually transitting to the hexagonal to rhomboidal cells of the median and distal portions of the leaf"	33
17	"Rhizoids deep red-brown, sparingly papillose to almost smooth, arising from a line of nematogons arranged in a single row along abaxial line of leaf insertion"	"Brachymenium systylium"
17	"Rhizoids of various colors, strongly papillose with nematogons not arranged in a single transverse row on stem"	18
18	"Costa not reaching leaf apex; leaves broadly ovate and deeply concave without a well-defined limbidium; clones easily fragmented into the constituent individual axes"	"Bryum gemmascens"
18	"Plants not in all respects as above"	19
19	"Plants mostly more than 1 cm high with leaves somewhat contorted distally; leaves with margins somewhat recurved"	20
19	"Plants smaller with leaves closely imbricate, not contorted"	21
20	"Leaves with a strong reddish coloration"	"Bryum muehlenbeckii"
20	"Leaves green"	"Bryum gemmiparum"
21	"Bulbils present in upper leaf axils, becoming visible by their growth that causes leaf spreading; costa percurrent; stems mostly less than 1 cm long"	22
21	"Bulbils not in leaf axils but with rhizoidal tubers functioning in asexual reproduction"	26
22	"Plants with a brownish to reddish-brown spinose awn at least on the distal portions of the leaves"	"Brachymenium exile"
22	"Plants with awn concolorous with rest of leaf or with the costa not excurrent"	23
23	"Bulbils mostly 1-2 per upper leaf axil, usually with leaf primordia well developed, several cells wide at base"	"Bryum bicolor"
23	"Bulbils 2-5 per upper leaf axil"	24
24	"Bulbils small, 100-200 µm in diameter; primordia absent or difficult to define"	"Bryum gemmilucens"
24	"Bulbils larger, with obvious leaf primordia on their distal portions"	25
25	"Bulbils with leaf primordia blunt to broadly acute at apices, mostly more than 250 µm in diameter"	"Bryum barnesii"
25	"Bulbils with leaf primordia narrow and needle like, mostly less than 250 µm in diameter"	"Bryum gemmiferum"
26	"Rhizoidal tubers red to red-brown with individual cells strongly protuberant or mammillose bulging"	27
26	"Rhizoidal tubers variously colored, smooth on surface with individual cells not bulging"	28
27	"Limbidium well-defined at mid-leaf; rhizoidal tubers mostly more than 125 µm in diameter"	"Bryum rubens"
27	"Limbidium absent or inconspicuous; rhizoidal tubers mostly less than 100 µm in diameter"	"Bryum klinggraeffii"
28	"Rhizoidal tubers brown"	29
28	"Rhizoidal tubers red to yellow"	30
29	"Rhizoidal tubers mostly not spherical, often pyriform, to 75 µm in longest diameter"	"Bryum pyriferum"
29	"Rhizoidal tubers spherical, more than 125 µm in diameter; costa long excurrent"	"Bryum radiculosum"
30	"Rhizoidal tubers produced on violet rhizoids"	"Bryum violaceum"
30	"Rhizoidal tubers produced on brownish rhizoids"	31
31	"Rhizoidal tubers yellow, less than 100 µm in diameter"	"Bryum tenuisetum"
31	"Rhizoidal tubers red to yellow, larger"	32
32	"Many of the internal basal cells of the leaf short rectangular; rhizoidal tubers yellow or with a yellowish blush"	"Bryum subapiculatum"
32	"Basal cells of the leaf consistently quadrate; rhizoidal tubers reddish"	"Bryum microerythrocarpum"
33	"Leaves broadest above or at the middle and thus appearing obovate"	34
33	"Leaves broadest near the base"	42
34	"Plants with filiform gemmae present in upper leaf axils"	35
34	"Plants without such filiform gemmae"	36
35	"Leaves decurrent with limbidium reaching nearly or completely to the leaf apex; costa percurrent to short excurrent; gemmae long and mostly unbranched, strictly axillary in insertion"	"Bryum flaccidum"
35	"Leaves not decurrent with limbidium mostly very weak or absent at leaf apex; costa weak, mostly ceasing before leaf apex; gemmae extensively branched, inserted in leaf axils and on leaf base"	"Bryum laevifilum"
36	"Leaves evenly spaced, not rosulate, somewhat glaucous, laterally twisted when dry"	37
36	"Leaves rosulate on stems, green, erect or clockwise twisted around stem when dry"	38
37	"Leaf lamina orbicular to broadly ovate; limbidium confluent with costa at apex; plant glaucous"	"Bryum elegans"
37	"Leaf lamina elliptical, 2.5-3.5:1; limbidium ending before leaf apex; plant glossy"	"Brachymenium spirifolium"
38	"Rosulate comas forming interrupted tufts; costa short excurrent with awn reflexed back from plane of leaf; limbidium poorly defined above the leaf middle"	"Bryum canariense"
38	"Stems usually with only a single rosulate cluster; excurrent costa not reflexed; limbidium various"	39
39	"Leaves distinctly decurrent, mostly washed with red even distally; costa percurrent to short excurrent"	"Bryum erythroloma"
39	"Leaves not decurrent, reddened only near base; costa various"	40
40	"Limbidium weak or absent above; margins near apex nearly entire; innovational branchlets below perichaetia with leaves broader and shorter, nearly imbricate"	"Bryum gemmascens"
40	"Limbidium strong even near leaf apex; margins near apex serrulate to serrate; innovational branchlets with leaves similar to leaves of main branches"	41
41	"Plant synoicous or autoicous; leaves erect but contorted when dry; capsule with reddish coloration when mature"	"Bryum torquescens"
41	"Plant dioicous; leaves clockwise twisted around stem when dry; capsule mostly brown when mature"	"Bryum capillare"
42	"Leaves without a defined limbidium; costa subpercurrent, percurrent or only minutely excurrent"	43
42	"Leaves with limbidium obvious to near apex; costa evidently excurrent"	44
43	"Median leaf cells short hexagonal, more than 20 µm broad; leaf apex obtuse with costa mostly ceasing below apex"	"Bryum muehlenbeckii"
43	"Median leaf cells linear, more than 6:1, less than 10 µm broad; leaf apex acute with costa ending at apex"	"Bryum alpinum"
44	"Leaves comosely arranged at stem apices; capsule mostly less than 2.5:1; limbidium broad with at least 5 rows of cells at leaf apex"	45
44	"Leaves equidistantly arranged along stem; capsule mostly longer; limbidium present throughout but more narrow"	47
45	"Leaves with costa shorter and with the lamina not so gradually contracted"	"Bryum knowltonii"
45	"Leaves distally narrowly acute, gradually contracted to an excurrent costa that exceeds 0.5 mm in length"	46
46	"Endostome and exostome fused with space between the two rows of teeth forming small chambers; capsule red"	"Bryum algovicum"
46	"Endostome and exostome not so fused; capsule yellow to orange"	"Bryum amblyodon"
47	"Leaves narrowly decurrent but with decurrency reaching nearly to base of next leaf; basal cells thick-walled with lumen:wall ratio about 4-6:1, and with these cell walls irregularly thickened to pitted"	48
47	"Leaves not so strongly decurrent; basal cells not so strongly thick-walled, never pitted"	49
48	"Plant synoicous"	"Bryum bimum"
48	"Plant dioicous"	"Bryum pseudotriquetrum"
49	"Leaf cells seldom more than 2.5-3:1, broadly hexagonal; limbidium broader"	50
49	"Upper leaf cells on distal leaves at least in part long rhomboidal, 5-6:1; limbidium only 2-3 cells wide near leaf apex"	51
50	"Endostome processes with perforations as broad as long; spores 12-16 µm in diameter"	"Bryum lisae"
50	"Endostome processes with perforations to twice as broad as long; spores 18-20 µm in diameter"	"Bryum pallescens"
51	"Leaves with spinose awn that is more than 1/2 as long as the leaf lamina"	"Bryum badium"
51	"Leaves with nearly smooth awn that is less than 1/2 as long as the leaf lamina"	"Bryum caespiticium"