By Nickte Mendez
Department of Biology, California State University, Northridge, CA 91330-8303
Editor: paul.wilson@csun.edu
Examine characters in the following order.
1. Leaves. Dry leaves are either contorted or ± erect (for photos, see Couplet A). Only a few species of Orthotrichum have contorted leaves, so much of the family can be eliminated based on this one obvious character.
2. Height of capsule relative to leaves. Determine the degree to which the capsule is immersed, emergent, or exserted (Couplet X). An immersed capsule has leaves extending beyond the mouth. An emergent capsule has leaves covering the lower part of the capsule. An exserted capsule is on a longer seta that is surrounded by leaves whose tips do not extend to the base of the capsule.
3. Capsule ribbing. Capsules, when dry, vary from smooth (unribbed), to weakly ribbed, to strongly ribbed (Couplet AF). A weakly ribbed capsule is ribbed longitudinally from just below the mouth to about the middle of the urn. A strongly ribbed capsule is ribbed to near the base of the urn. The number of ribs on the capsule also varies: eight ribs, 16 ribs, or eight strong ribs alternating with eight weak ribs. Species vary in the degree to which capsules are constricted below the mouth when dry, and in general, the more constricted the capsule, the stronger the ribbing.
4. Peristome. In many Orthotrichaceae the peristome is double. If so, the capsule mouth will have exostome teeth and endostome segments (visible through a good dissecting microscope; Couplet AX). The number of exostome teeth can be zero, eight, or 16. Species with eight teeth will have teeth that are four cells wide. Species with 16 teeth will have teeth that are two cells wide. In intermediate cases, eight teeth may be partially split longitudinally. The number of endostome segments can also be zero, eight, or 16. Endostome segments are usually a single cell wide in Orthotrichum.
Next, dissect the specimen. Take a shoot, and moisten it on a microscope slide. Pull numerous leaves off of the stem from their bases. Make cross-sections of multiple leaves, one at a time, at two-thirds distally. Select a sporophyte that has an intact peristome. If only unopened capsules are available, pluck the most mature one, make a wet mount, and try to boil off the operculum by holding the slide over a flame. If only old capsules are available, try to find one with some peristome parts. Regardless, slice the capsule longitudinally, and splay out the halves with the exterior up. Add a coverslip, and if necessary, boil away air bubbles.
5. Gemmae. Gemmae in Orthotrichum, when present, grow on the leaf surface. They are often rust colored. At maturity, they abscise and function as asexual propagules. Orthotrichum lyellii has very prominent gemmae, which can be observed with the naked eye. Gemmae in other species may be much smaller, and observable only with a microscope (100×; Couplet J).
6. Microscopic leaf characters. Many useful characters pertain to the shape of leaves, their apex, margin, and thickness. The apex of the leaf can end acutely without differentiated cells, with a mucron (short accentuated tip), or with a hyaline awn (a pigmentless extension of the costa beyond the lamina). The number of cell layers is best examined in cross-sections in the distal two-thirds of the leaf, as this is where species differ. Species vary from being unistratose, to having bistratose streaks, to being fully bistratose beyond approximately the midleaf. In some species with a unistratose lamina, the leaf margins may be bistratose, or even tristratose (Couplet Q). Leaf margins are usually recurved, but a few species distinctively have plane margins. Lastly, leaf papillae can be single or forked, and their location (over the lumens or over the cell walls) can vary, and where they are prominent on the leaf (on the distal third) can be diagnostic.
7. Stomata. Stomata are observed on a longitudinal section of the capsule. Stomata are either phaneroporous or cryptoporous (Couplet S). When stomata are phaneroporous, exothecial cells abut guard cells in the same plane. When stomata are cryptoporous, guard cells are recessed and may be partly covered or almost completely covered by specialized subsidiary cells.
8. Ornamentation of exostome teeth. The outer surface of exostome teeth may be nearly smooth, or have coarse papillae, or have fine papillae, and sometimes papillae swirl into finger-print-like striations (Couplet AN).
9. Hairs of calyptra and of vaginula. Calyptrae may be hairless or hairy, with hairs straight or wavy. Distinctive hairs may also occur on the vaginula, which is the collar that surrounds the base of the developing sporophyte. Microscopically (400×), hairs may be smooth or papillose (Couplet I).
10. Axillary hairs. Axillary hairs are organs adaxial to a leaf where it joins a stem (Couplet AU). They are best seen (400×) when still attached after tearing most of the leaf off of its shoot. Axillary hairs are unusually long in a few species of Orthotrichum, whereas most species of Orthotrichum have axillary hairs that are about the same length as in other mosses.
A. Leaves weakly crispate to contorted when dry ..... B
A' Leaves ± erect when dry ..... J
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| Orthotrichum pulchellum crispate leaves (Norris 74989, UC 1673879) | Orthotrichum flowersii erect leaves (Coleman 1350) |
B. Apex of leaf usually filiform, uniseriate, 2–5 cells long ..... C
B' Apex of leaf not uniseriate ..... D
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| Zygodon rupestris filiform apex (Wilson 5050, SFV 21569) | Orthotrichum norrisii leaf apex blunt (Shevock 32529, UC 1933675) |
C. Plant stoloniferous with prostrate axes possessing abundant red-brown rhizoids; gemmae absent; erect branches short, not hamate when dry; leaf ovate with a long acumen, mid-laminal cells pluripapillose with papillae more than half the thickness of cells in cross-section ..... Ulota megalospora
C' Plant erect and tufted; abundant gemmae in leaf axils; stem apices of dry plant strongly hamate; leaf lanceolate, mid-laminal cells pluripapillose with 2–4 papillae per cell, papillae much less than half the thickness of cells in cross-section ..... Zygodon rupestris
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| Ulota megalospora prostrate axes with abundant red-brown rhizoids (Wilson 206, SFV 20008) | Zygodon rupestris erect and tufted, lacking red-brown rhizoids (Wilson 5050, SFV21569) |
D. Margins serrulate; apical cell longer than cells of lamina; basal marginal cells quadrate to very short rectangular, abruptly differentiated into several rows from more elongate interior basal cells; capsules exserted with a long and well-demarcated neck; stomates phaneroporous ..... E
D' Margins entire; apical cell same length-to-width ratio as cells of distal lamina; basal marginal cells not so abruptly differentiated; capsules and stomates various ..... F
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| Ulota obtusicula serrulate leaf margins (Norris 78463, SFV 20907) | Orthotrichum pulchellum leaf apex (Norris 75064, UC 1650214) |
E. Apex of leaves toward shoot tip with a reddish-brown cluster of septate gemmae; occurring within ~1 km of ocean ..... Ulota phyllantha
E' Apex of leaves not gemmiparous; moss more widely distributed ..... Ulota obtusicula
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| Ulota phyllantha leaf apices with gemmae cluster (Wilson 537, SFV 20009) | Ulota obtusicula leaf apices lacking gemmae (Norris 78463, SFV 20907) |
F. Exostome ± red; exothecial bands mostly 2 cells wide ..... Orthotrichum pulchellum
F' Exostome not red; exothecial bands mostly 4–6 cells wide ..... G
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| Orthotrichum pulchellum highly recurved ± red exostome teeth (Norris 75064, UC 1650214) | Orthotrichum consimile exostome teeth not red (Norris 50401, UC 1722823) |
G. Endostome in 16 segments (sometimes 8 of them reduced alternating with 8 that are more prominent), inner peristome layer with conspicuous longitudinal striae; operculum with a red basal rim; seta commonly 2.5–5.5 mm long; calyptra naked ..... Orthotrichum columbicum
G' Endostome in 8 segments, inner peristome layer smooth or weakly papillose; operculum with a thin orange basal rim; seta commonly 1.0–2.0 mm; calyptra naked or with ± abundant hairs ..... H
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| Orthotrichum columbicum 16 endostome segments (Shevock 41858, CAS 1187203) | Orthotrichum consimile 8 endostome segments (Dillingham 2006, UC 1932571) |
H. Leaf margins plane (sometimes one leaf margin recurved); leaf apex various, not filiform; rhizoids rough, not noticeably ascending along stem; vaginula hairy; calyptra ± hairy; stomata in proximal half of urn and neck ..... Orthotrichum persimile
H' Leaf margins recurved; leaf apex commonly filiform; rhizoids smooth, ascending along stems; vaginula naked or very sparsely hairy; calyptra naked or hairy; stomata usually in middle of urn (rarely in proximal half, never on neck) ..... I
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| Orthotrichum persimile plane leaf margins (Medina et al. 2012. Taxon 61: 1180–1198) | Orthotrichum consimile recurved leaf margins (Medina et al. 2012. Taxon 61: 1180–1198) |
I. Calyptra with abundant to scarce papillose hairs; vaginula (0.25)0.4–0.8 mm long, naked or with sparse papillose hairs; leaf apex merely following the curve of the leaf ..... Orthotrichum consimile
I' Calyptra naked, rarely with very few inconspicuous smooth hairs; vaginula very long, (0.6)0.8–1.1(1.3) mm, naked; leaf apex distinctly unguiculate ..... Orthotrichum confusum
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| Orthotrichum consimile papillose calyptra hairs (Dillingham 2006, UC 1932571) | Orthotrichum confusum smooth calyptra hairs (Medina et al. 2012. Taxon 61: 1180–1198) |
J. Gemmae present (appearing as brown multicellular warts on leaves) ..... AZ—bypass for mosses with gemmae, does not rely on sporophytes
J' Gemmae absent ..... K—species with gemmae can be keyed via this lead, though with greater difficulty
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| Orthotrichum obtusifolium gemmae present on leaf (Norris 68813, UC 1643011) | Orthotrichum cupulatum, gemmae absent from leaf (Norris 87675, UC 1759893) |
K. Cells above the base of the leaf and inward from the margin with high, pointed papillae inserted not on lumen but on lateral walls; dioicous; leaf apices either very long and somewhat flexuose when dry or with apex bluntly eroded by gemma production ..... L
K' Papillar arrangement not as above (proximal cells smooth or papillose over the lumen); monoicous; leaf apices usually not long and flexuose; gemma production various ..... M
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| Orthotrichum papillosum high pointed papillae on walls of proximal cells (Norris 83851, UC 1774498) | Orthotrichum rupestre papillae on lumens of proximal cells (Coleman 1651) |
L. Gametophytes usually densely covered with brown wart-like multicellular gemmae; leaves not long acuminate ..... 2Orthotrichum lyellii sensu stricto
L' Gametophytes without gemmae; leaves usually having a long, slightly serrulate acumen ..... Orthotrichum papillosum
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| Orthotrichum lyellii with gemmae covering leaves (Coleman 2) | Orthotrichum papillosum without gemmae (Wilson 5358) |
M. Distal leaf lamina bistratose or at least with some bistratose streaks ..... N
M' Leaf lamina unistratose ..... R
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| Orthotrichum bolanderi distal portion of leaf lamina bistratose (Norris 81945, UC 1774444) | Orthotrichum rupestre unistratose leaf lamina (Coleman 1651) |
N. Stomata phaeneroporous; gametophytes in loose wefts with shoots often greater than 1 cm long ..... Orthotrichum bolanderi
N' Stomata cryptoporous; ascending shoots less than 1 cm long ..... O
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| Orthotrichum bolanderi gametophytes in loose wefts (© John Game) | Orthotrichum cupulatum gametophytes in short tufts (© Scott Loring) |
O. Gametophytes consisting of prostrate stems giving rise to differentiated vegetative and fertile uprights (unlike other Orthotrichum species); vegetative leaves nearly obtuse; on sandstone ..... 2Orthotrichum kellmanii
O' All stems of the same sort, in tufts (like other Orthotrichum species); on limestone or granite ..... P
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| Orthotrichum kellmanii fertile leaves (left) and sterile vegetative leaves (right) (Shevock 29890, UC 1872681) | Orthotrichum hallii undifferentiated stems and leaves (Norris 18242) |
P. Mature capsules with 16 ribs; distal part of leaf mainly unistratose with bistratose streaks (margins not thicker) ..... 2Orthotrichum cupulatum
P' Mature capsule with 8 prominent ribs or with 8 faint ribs between 8 prominent ribs; distal part of leaf uniformly bistratose its full width or margins bi- to tristratose ..... Q
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| Orthotrichum cupulatum caspules with 16 ribs and 16 erect exostome teeth (Norris 84832, UC 1759913) | Orthotrichum shevockii immersed capsule, strongly 8 ribbed (Norris 87128, UC 1759935) |
Q. Leaf margins not thicker than leaf lamina; capsule immersed to emergent; exostome teeth 8 or irregularly split into 16, erect or spreading; leaf papillae small and conical; gametophyte ± green in clumps of short shoots ..... Orthotrichum hallii
Q' Leaf margin thicker (more cells) than leaf lamina, sometimes lamina also with bistratose streaks; capsule immersed; exostome 8; leaf papillae high, simple to forked ..... 2Orthotrichum shevockii
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| Orthotrichum hallii nearly uniformely bistratose (Norris 80330, UC 1757602) | Orthotrichum shevockii leaf margins bi- to tristratose (Norris 87128, UC 1769935) |
R. Margins incurved to plane throughout; gametophyte green, often with a ± red-brown cast; lamina unistratose; epiphytic, in mountains, often near running water ..... 2Orthotrichum obtusifolium
R' Margins recurved to revolute at least at base and usually along most of leaf; plant color various; lamina unistratose or not; habitat various ..... S
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| Orthotrichum obtusifolium plane leaf margins (Norris 68813,UC 1643011) | Orthotrichum pylaisii recurved leaf margins (Coleman 1010) |
S. Stomata phaneroporous as seen in longitudinal section of capsule; usually basal cells elongate, somewhat porose or with sinuose walls ..... T
S' Stomata cryptoporous; usually basal cells short-rectangular with evenly thickened walls ..... AH
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| Orthotrichum holzingeri phaneroporous stomata (Norris 70467, UC 1649719) | Orthotrichum norrisii cryptoporous stomata (Shevock 32529, UC 1933675) |
T. Exostome reduced to few basal plates or to narrow endostome segments ..... U
T' Exostome fully developed ..... V
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| Orthotrichum spjutii peristome reduced (Shevock 14898, UC 1754439) | Orthotrichum laevigatum fully developed peristome (Wilson 4486, SFV 21283) |
U. Gametophyte glaucous (due to very high multifid papillae); endostome absent; adaxial face of costa covered by laminal cells in at least distal third of leaf; spores to 11 μm in diameter ..... Orthotrichum spjutii
U' Gametophyte not glaucous; endostome in 8 segments; adaxial face of costa with elongate cells throughout; spores >11 μm ..... Orthotrichum acuminatum
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| Orthotrichum spjutii leaf cross-section, single and multifid papillae (Shevock 14898, UC 1754439) | Orthotrichum acuminatum leaf cross-section, low papillae (Shevock 32571, CAS 1146075) |
V. Leaves smooth distally ..... W
V' Leaves papillose distally ..... X
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| Orthotrichum holzingeri smooth leaves (Norris 70467, UC 1649719) | Orthotrichum laevigatum papillose leaves (Wilson 4486, SFV 21283) |
W. Calyptra hairless; peristome smooth; on volcanic rock ..... Orthotrichum holzingeri—endemic of volcanic plateaus of northeastern California and neighboring states to the northeast.
W' Calyptra hairy; peristome papillose; usually epiphytic ..... 2Orthotrichum shawii
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| Orthotrichum holzingeri smooth exostome teeth (Norris 70467, UC 1649719) | Orthotrichum shawii papillose exostome teeth (Shevock 24632, CAS 1113091) |
X. Capsule fully exserted with base of capsule beyond parichaetial leaves (side branch may extend in parallel) ..... Y
X' Capsule emergent to immersed ..... AB
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| Orthotrichum pylaisii exserted capsules (Coleman 1010) | Orthotrichum rupestre weakly emergent capsule (Coleman 1651) |
Y. Capsule weakly 8-ribbed, short-oblong gradually expanding from seta (less than 3:1 although difficult to judge); exostome teeth recurved to reflexed with age when dry; leaves broad distally (not acuminate, at two-thirds their length greater than half of their width) ..... Z
Y' Capsule weakly ribbed to not ribbed, cylindric (>3:1); exostome teeth typically erect to spreading with age when dry; leaves lanceolate (at least some somewhat acuminate) ..... AA
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| Orthotrichum pylaisii weakly ribbed capsule, exostome recurved when dry with age (Coleman 1010) | Orthotrichum laevigatum capsules ± smooth (Wilson 4486, SFV 21283) |
Z. Endostome segments one cell wide, smooth or finely papillose; leaf ovate-lanceolate to lanceolate ..... Orthotrichum pylaisii
Z' Endostome segments with remnants of a second cell width, coarsely and strongly papillose; leaf lanceolate to narrowly lanceolate ..... 2Orthotrichum speciosum
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| Orthotrichum pylaisii endostome segment one cell wide (Coleman 1010) | Orthotrichum speciosum endostome with remnants of a second cell width (Norris 68877, UC 1723786) |
AA. Leaves bluntly acute to obtuse; mid-laminal cells mostly rather low papillose; adaxial surface of costa with elongate to linear, thick-walled cells above its middle ..... Orthotrichum laevigatum—compared to Orthotrichum pylaisii, the gametophyte is smaller.
AA' Leaves long-acuminate to narrowly acute; mid-laminal cells with papillar salients at least as high as one-half of cell thickness; adaxial surface of costa covered with cells like those of adjacent lamina above its middle ..... Orthotrichum macounii—not recognized as distinct from Orthotrichum laevigatum by Vitt (2014).
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| Orthotrichum laevigatum adaxial surface; costa with elongate, thick– walled cells (Wilson 4486, SFV 21283) | Orthotrichum macounii adaxial surface; costa with cells like those of adjacent lamina (MacFadden 19054, CAS 441460) |
AB. Exostome generally separated into 16 teeth; capsules immersed to emergent ..... AC
AB' Exostome generally of 8 teeth with pairs not separated; capsules emergent ..... AF
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| Orthotrichum shawii exostome separated into 16 teeth (Shevock 24632, CAS 1113091) | Orthotrichum affine exostome of 8 teeth (Norris 68516, SFV 20954) |
AC. Capsule smooth; exostome papillose ..... Orthotrichum striatum—exostome 16, endostome 16.
AC' Capsule ribbed at least in distal half; exostome papillose to nearly smooth ..... AD
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| Orthotrichum striatum smooth capsule; exostome 16, endostome 16 (© Helge G. Gundersen) | Orthotrichum rupestre nearly smooth exostome (Coleman 1651) |
AD. Capsule emergent, weakly ribbed with metallic glints; exostome teeth tending to recurve with age; usually epiphytic ..... 2Orthotrichum shawii—exostome 16, endostome 8 short segments.
AD' Capsule immersed, ribbed entire length of capsule, without metallic glints; exostome teeth erect; usually epilithic ..... AE
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| Orthotrichum shawii emergent capsule with metallic-copper sheen (Shevock 24632, CAS 1113091) | Orthotrichum rupestre immersed capsule without copper sheen (Coleman 1651) |
AE. Gametophytes growing as relatively large, loose mats; exostome low papillose to almost smooth ..... Orthotrichum rupestre—exostome 16, endostome, if present, 8.
AE' Gametophytes growing in small, closely aggregated tufts; exostome densely papillose ..... Orthotrichum texanum—not recognized as distinct from Orthotrichum rupestre by Vitt (2014); exostome 16, endostome, if present, 8.
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| Orthotrichum rupestre nearly smooth exostome (Wilson 5359) | Orthotrichum texanum densely papillose exostome (Hermann 20411, CAS 469527) |
AF. Capsule ribbed only in distal half ..... 2Orthotrichum speciosum—endostome 8, exostome 8.
AF' Capsule ribbed more than half its length ..... AG
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| Orthotrichum speciosum capsule weakly ribbed (Norris 68877, UC 1723786) | Orthotrichum franciscanum capsule ribbed more than half its length (Shevock 20202, CAS 1193149) |
AG. Capsule long-cylindric to cylindric (widest proximally when old); exostome 8, endostome segments often 8, rarely 16; leaf apices acute, not generally bleached; generally living on bark ..... Orthotrichum affine
AG' Capsule ovate-oblong to oblong-cylindric (widest distally when old); exostome teeth 8, endostome segments 16; leaf apices acuminate, cuspidate, often bleached ..... Orthotrichum praemorsum—compared to O. pylaisii with its emergent to exserted capsules, O. praemorsum has less emergent capsules that are more strongly ribbed.
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| Orthotrichum affine cylindric capsule, 8 endostome segments (Norris 68516, SFV 20954) | Orthotrichum praemorsum oblong capsule, 16 endostome segments (Shevock 22039, CAS 1040112) |
AH. Leaves terminating in hyaline awn; terminal cell of leaf elongate (more than three times as long as mid-laminal cells) ..... AI
AH' Leaves without hyaline awn ..... AJ
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| Orthotrichum diaphanum leaf with hyaline awn (Shevock 19240, UC 1739285) | Orthotrichum euryphyllum leaf lacking hyaline awn (Shevock 32504, UC 1933798) |
AI. Leaves terminating in a hyaline awn of one or a few cells; exostome teeth 8; endostome segments 8; gemmae absent ..... Orthotrichum franciscanum
AI' Leaves terminating in an awn of many hyalline cells; exostome teeth 16; endostome segments 16; gemmae often present ..... 2Orthotrichum diaphanum
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| Orthotrichum franciscanum hyaline awn of one cell (Shevock 20202, CAS 1193149) | Orthotrichum diphanum many hyaline cells (Cardenas 5637, UC 1779402) |
AJ. Exostome absent (endostome present); capsules puckered at mouth by 8 short ribs; calyptra hairy ..... AK
AJ' Exostome present; capsules various (many species not particularly constricted at mouth); calyptra hairy or hairless ..... AL
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| Orthotrichum mazimpakanum exostome absent, endostome present with mouth puckered by 8 short ribs (Garilleti et al. 2011. The Bryologist 114: 346-355) | Orthotrichum underwoodii exostome teeth present (Toren 9511, CAS 1048109) |
AK. Endostome segments 16, very apparent when dry, ± white, strongly papillose, widely covering mouth; capsule mouth star-shaped when dry; vaginula naked or with scattered thin and smooth hairs; operculum convex, mucronate, without differentiated basal rim; leaf margin and lamina unistratose ..... Orthotrichum anodon
AK' Endostome segments usually 8, inconspicuous when dry, hyaline, smooth, sparse around mouth; capsule mouth round when dry; vaginula hairy, with thick papillose hairs; operculum slightly convex and short rostrate, with bright orange rim; leaf margins bistratose, distal leaf lamina partially to almost completely bistratose ..... Orthotrichum mazimpakanum
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| Orthotrichum anodon endostome segments ± white, covering mouth (Garilleti et al. 2006. The Bryologist 109: 188-196) | Orthotrichum mazimpakanum exostome segments inconspicuous, sparse around mouth (Garilleti et al. 2011. The Bryologist 114: 346-355) |
AL. Leaf apex rounded-obtuse, often somewhat toothed; leaves smooth to inconspicuously papillose; costa sinuose; mosses seasonally inundated ..... AM
AL' Leaf apex acute to acuminate or mucronate, usually entire; leaves smooth to densely papillose; costa straight; mosses not typically inundated ..... AN
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| Orthotrichum rivulare rounded-obtuse leaf apex, toothed, sinuose costa (Norris 100722, UC 1759034) | Orthotrichum shevockii acute leaf apex, not toothed (Norris 87128, UC 1759935) |
AM. Gametophytes dark green to nearly black, sometimes dark-red brown, in compact tufts; apex entire to irregularly serrulate; distal laminal cells approaching 20 μm; epilithic, in headwaters ..... Orthotrichum euryphyllum
AM' Gametophytes rich dark green, sometimes black on older portions, in loose patches; apex irregularly dentate; distal laminal cells mostly to 12 μm; epiphytic or epilithic, in frequently inundated flood-plains of large streams ..... Orthotrichum rivulare
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| Orthotrichum euryphyllum slightly serrulate apex (Shevock 32504, CAS 1111476) | Orthotrichum rivulare irregularly dentate apex (Lenz 630, UC 1920649) |
AN. Exostome erect or spreading, with striate ridges on dorsal face resembling a fingerprint pattern; endostome absent; leaves often with bistratose streaks; epilithic ..... AO
AN' Exostome reflexed to recurved, papillose to papillose-striate but never with a fingerprint-like pattern; endostome present; leaves unistratose or bistratose margins distal two-thirds of leaf; most species epiphytic ..... AQ
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| Orthotrichum cupulatum striate ridges on exostome teeth (Norris 84832, UC 1759913) | Orthotrichum norrisii papillose exostome (Shevock 32529, UC 1933675) |
AO. Capsule exserted and cylindrical, mostly with 8 long ribs alternating with 8 short ones ..... Orthotrichum anomalum—not yet verified from CA but reported from NV and OR.
AO' Capsule immersed to emergent; with 8 or 16 ribs ..... AP
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| Othotrichum anomolum exserted capsules with 8 ribs and 8 alternating short ribs (Allen 29190. CAS 1135847) | Orthotrichum cupulatum capsules immersed to emergent (Norris 84832, UC 1759913) |
AP. Capsule with 16 ribs; leaves very weakly keeled, acute; gametophyte not glaucous ..... 2Orthotrichum cupulatum
AP' Capsule with 8 ribs; leaves distally keeled, obtuse to bluntly acute; gametophyte glaucous ..... Orthotrichum pellucidum
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| Orthotrichum cupulatum capsule emergent with 16 ribs (Norris 84832, UC 1759913) | Orthotrichum pellucidum capsule with 8 ribs, plant glaucous (Shevock 32482, UC 1933690) |
AQ. Leaf margins bistratose in distal two-thirds of leaf; capsules immersed with seta less than 0.5 mm long ..... 2Orthotrichum shevockii
AQ' Leaf margins unistratose; length of seta various ..... AR
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| Orthotrichum shevockii bistratose leaf margins (Norris 87128, UC 1759935) | Orthotrichum cucullatum capsules emergent (Norris 106515, UC 1768584) |
AR. Capsules fully exserted with seta visible ..... 2Orthotrichum coulteri
AR' Capsules immersed to emergent ..... AS
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| Orthotrichum coulteri exserted capsules (Norris 109508, UC 1917203) | Orthotrichum flowersii emergent capsule (Coleman 1350) |
AS. Capsule more than four times as long as wide when wet ..... AT
AS' Capsule much less than four times as long as wide when wet ..... AV
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| Orthotrichum norrisii urn longer than wide (Shevock 32529, UC 1933675) | Orthotrichum alpestre urn wide (Shevock 14804, UC 1712492) |
AT. Leaf apices obtuse or rounded and frequently cucullate ..... 2Orthotrichum cucullatum
AT' Leaf apices acute and flat to channeled ..... AU
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| Orthotrichum cucullatum obtuse leaf apex (Norris 80668, UC 1768584) | Orthotrichum norrisii acute leaf apex (Norris 55099A, UC 1757638) |
AU. Distal leaf lamina unistratose with rarely scattered bistratose ridges; basal marginal cells often quadrate, thick walled; axillary hairs 700–1200 μm long, multiseriate and branched, in dense fascicles, forming tomentum on stems; leaves distinctly narrowed with strongly revolute margins in distal half of leaf; apex acuminate to subulate ..... 2Orthotrichum pilosissimum—not yet verified from CA, reported from NV.
AU' Leaf lamina unistratose entire length; basal marginal cells thin walled, occasionaly thick walled and nodose; axillary hairs 75–250 μm long, filiform or subclaviform, uniseriate, not branched; leaves broader .....2Orthotrichum norrisii
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| Orthotrichum pilosissimum axillary hairs long, branched, multiseriate (Shevock 22397, CAS 1040002) | Orthotrichum norrisii axillary hairs short, unbranched, and uniseriate (Shevock 32529, UC 1933675) |
AV. Tip of leaf nearly obtuse except for one-cell mucron; distal one-fourth of leaf tongue-shaped (after narrowing from broader basal half); calyptrae mostly hairless ..... 2Orthotrichum flowersii
AV' Tip of leaf acute; distal one-fourth of leaf triangular; calyptrae hairy to nearly hairless ..... AW
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| Orthotrichum flowersii apex with one-celled mucron (Coleman 1350) | Orthotrichum alpestre acute leaf tip (Shevock 14804, UC 1712492) |
AW. Subsidiary cells with strongly thickened radial walls that obscure outline of guard cells below; leaf papillae high, sometimes branched; exostome teeth striate-papillose distally ..... AX
AW' Subsidiary cells around stomates without thickened radial walls, thickened only at tips, thus guard cells only partially covered by subsidiary cells; leaf papillae low; exostome teeth uniformly papillose, not striated distally..... AY
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| Orthotrichum alpestre with strongly thickened radiall walls, obscuring outline of guard cells (Shevock 14804, UC1712492) | Orthotrichum pumilum subsidiary cells thickened only at tips, guard cells somewhat covered (Norris 77959, UC1675390) |
AX. Capsules ribbed throughout, short-cylindric; exostome teeth 16, erect when mature, reflexed when old; endostome teeth 16, filiform ..... Orthotrichum underwoodii—endemic to Santa Clara mountains, below 2000 m elevation.
AX' Capsules lightly ribbed primarily toward strangulate mouth, mostly oblong in shape; exostome teeth 8, reflexed; endostome with 8 segments ..... Orthotrichum alpestre—widespread above 2000 m elevation.
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| Orthotrichum underwoodii peristome with 16 endostome and 16 exostome teeth (Toren 9511, CAS 1048109) | Orthotrichum alpestre peristome with 8 endostome and 8 exostome teeth (Shevock 14804, UC 1712492) |
AY. Leaves parallel-sided from half to three-fourths distally; endostome with 16 segments; calyptra plicate; capsule gradually tapering to seta; distal laminal cells less than 14 μm ..... Orthotrichum pallens
AY' Leaves gradually tapering from base to three-fourths of total length; endostome with 8 segments; calyptra smooth; capsule abruptly narrowing into seta; distal laminal cells more than 13 μm; gemmae sometimes present ..... 2Orthotrichum pumilum
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| Orthotrichum pallens leaves parallel over three-fourths their length, calyptra plicate (© Michael Luth, US Department of Agriculture) | Orthotrichum pumilum leaf broadly lanceolate, tapering from a broad base (Norris 77959, UC 1675390) |
AZ. Multicellular gemmae densely covering leaves; pre-basal marginal cells with high pointed papillae on cell wall ..... 2Orthotrichum lyellii
AZ' Multicellular gemmae not densely covering leaves ..... BA
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| Orthotrichum lyellii gemmae densely covering leaves (Coleman 2) | Orthotrichum obtusifolium gemmae not densely covering leaves (Wilson 607, SFV 19764) |
BA. Leaves terminating in a hyaline awn ..... 2Orthotrichum diaphanum
BA' Leaf tip at most irregularly bleached, not hyaline ..... BB
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| Orthotrichum diaphanum leaf with hyaline awn (Shevock 19240, UC 1739285) | Orthotrichum obtusifolium leaf tip lacking hyaline awn (Norris 68813, UC 1643011) |
BB. Leaf lamina uniformly bistratose; gametophytes with prostrate stems consisting of differentiated vegetative and fertile uprights (unlike other Orthotrichum species); vegetative leaves nearly obtuse ..... 2Orthotrichum kelmanii—stomata cryptoporous.
BB' Leaf lamina unistratose or occasionally scattered bistratose streaks ..... BC
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| Orthotrichum kelmanii differentiated fertile (left) and vegetative (right) stems (Shevock 29890, UC 1872681) | Orthotrichum coulteri leaf lamina with bostratose streaks (Norris 109508, UC 1917203) |
BC. Each leaf cell with a single papilla over lumen on abaxial and adaxial surfaces ..... 2Orthotrichum obtusifolium
BC' Leaves smooth to having 1-3 small conic papillae per cell ..... BD
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| Orthotrichum obtusifolium single papilla on lumen on both abaxial and adaxial surfaces (Wilson 607, SFV 19764) | Orthotrichum pumilum leaves smooth (Norris 77959, UC 1675390) |
BD. Capsules fully exserted; subsidiary cells with strongly thickened radial walls that obscure outline of guard cells below; leaves not decurrent ..... 2Orthotrichum coulteri
BD' Capsules immersed to emergent ..... BE
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| Orthotrichum coulteri exserted capsules (Norris 109508, UC1917203) | Orthotrichum flowersii emergent capsules (Coleman 1350) |
BE. Leaf apices channeled ..... BF
BE' Leaf apices more or less flat, acute to acuminate, never channeled or cucullate ..... BG
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| Orthotrichum norrisii leaf apex channeled (Norris 55099A, UC 1757638) | Orthotrichum pumilum leaf apex flat (Norris 77959, UC 1675390) |
BF. Axillary hairs hyaline, distinctively long, protruding from foliose shoots; capsule cylindric, strongly constricted when dry; leaves unistratose or distal portion rarely with scattered bistratose streaks ..... 2Orthotrichum pilosissimum— not yet verified from CA, reported from NV.
BF' Axillary hairs not long, not protruding from foliose shoots; capsule cylindric, weakly or not constricted when dry; leaves unistratose ..... 2Orthotrichum norrisii
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| Orthotrichum pilosissimum axillary hairs distinctively long, hyaline (Shevock 22397, CAS 1040002) | Orthotrichum norrisii axillary hair (Shevock 32529, UC 1933675) |
BG. Tip of leaf nearly obtuse except for one-celled mucron; distal one-fourth of leaf tongue-shaped (after narrowing from broader basal half); calyptrae mostly hairless ..... 2Orthotrichum flowersii
BG' Tip of leaf acute; distal quarter of leaf triangular; calyptrae sparsely hairy ..... 2Orthotrichum pumilum
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| Orthotrichum flowersii leaf tip with one celled-mucron (Coleman 1350) | Orthotrichum pumilum triangular leaf tip (Norris 77959, UC 1675390) |