BFNA Title: Lembophyllaceae
Author: Various
Date: November 2, 2011
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Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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William R. Buck


Plants medium-sized to large, pale to dark green or golden, terrestrial, epipetric or epiphytic, often somewhat stipitate. Stems irregularly pinnate to regularly 2- or 3-pinnate, terete-foliate; cortex of small and incrassate cells; hyalodermis absent; pseudoparaphyllia foliose; paraphyllia absent; axillary hairs with 1--2 short, brown basal cells and 1--4 elongate, hyaline apical cells. Stem and branch leaves often differentiated, loosely appressed, mostly ovate and concave; costa single or double and short, sometimes stipe and stem leaves with a weak costa and branch leaves with a strong costa; median laminal cells short to linear, smooth or prorulose; alar cells mostly well differentiated, often excavate, mostly quadrate. Sexual condition dioicous. Seta mostly long, sometimes short, smooth or roughened throughout or just distally. Capsule cylindric, mostly erect and symmetric, but sometimes curved and horizontal; annulus typically differentiated; operculum conic to short-rostrate, straight; peristome typically perfect but sometimes reduced, exostome when not reduced cross-striolate on outer surface proximally, papillose distally, when reduced variously striate, papillose or smooth, endostome with high or low basal membrane, segments long and narrowly perforate, cilia nodose or appendiculate. Calyptra cucullate, smooth or slightly roughened, naked or hairy.


Genera 14, species ca. 50 (3 genera, 7 species in the flora): mostly south-temperate, but extending into the tropics and North Temperate Zone.


The bulk of genera and species of the Lembophyllaceae occur in the Southern Hemisphere, with only a few genera in the flora region. The plants tend to have terete-foliate stems with ovate, concave leaves. The costa is variable, sometimes on different leaves of the same plant. Many of the genera have perfect hypnoid peristomes, but there are genera (e.g., Bestia) with reduced peristomes. The calyptrae being frequently hairy is an unusual character in the flora region.


Selected References Crum, H. A. 1987. Bestia, Tripterocladium, and Isothecium: an explication of relationships. Bryologist 90: 40--42. Quandt, D., S. Huttunen, R. Tangney and M. Stech. 2009. Back to the future? Molecules take us back to the 1925 classification of the Lembophyllaceae (Bryopsida). Systematic Botany 34: 443--454.


1. Costa mostly short and double, rarely single (isolated leaves); branch and stem leaves well differentiated ………………………………………………………………. 3. Tripterocladium, p. XX

1. Costa consistently single; branch and stem leaves similar.

2. Median laminal cells less than 4:1; capsules erect with reduced peristomes ……. 1. Bestia, p. XX

2. Median laminal cells more than 5:1; capsules often inclined with perfect peristomes … 2. Isothecium, p. XX




1. BESTIA Brotherus in A. Engler & K. A. E. Prantl, Die natürlichen Pflanzenfamilien 1(3): 859. 1906 * [For George N. Best, 1846--1926, American bryologist]


James R. Shevock


Plants robust, forming large descending mats. Stems pinnate or irregularly 2-pinnate; branches generally curved to one side when dry. Leaves of stems and branches similar, ovate, broadly acute, somewhat concave at base, imbricate when dry but erect-spreading when moist; margins serrulate in distal 1/5; costa single, stout, distally toothed abaxially; laminal cells short, thick-walled, those in the distal portion of the leaf projecting at their distal ends as prorulae. Specialized asexual reproduction lacking. Capsules cylindrical, erect and symmetric; peristome double, well formed, somewhat reduced.


Species 1: Western North America, endemic to coastal California.


The genus Bestia has had a rather confusing taxonomic history causing difficulty in determining its family placement depending on which species of Bestia was critically examined and what combination of morphological characters were considered most important for inferring relationships (J. R. Shevock et al. 2008). H. A. Crum (1987) placed what was to become this unispecific genus in close relationship to Isothecium, in the Brachytheciaceae.  The other species, Bestia vancouveriensis was transferred to the Thamnobryaceae as Porotrichum vancouveriense (Kindberg ex Macoun) H.A. Crum, and subsequently elevated to generic rank as Bryolawtonia vancouveriensis. Bestia is a robust, distinctive species endemic to coastal California.


Although Bestia has been attributed to several families over the years, recent DNA studies suggest that both Bestia and Isothecium are closely related and should be transferred to the Lembophyllaceae. Bestia is morphologically similar in appearance to some species of Isothecium (especially I. myosuroides), but it has several gametophytic features that readily separate it, primarily median cells uniformly short (less than  4:1) whereas the juxtacostal cells in Isothecium are elongate to 8:1. The long, straight, cylindric capsules with smaller peristome teeth differ markedly from the rather hypnaceous curved capsules in Isothecium.


SELECTED REFERENCES Crum, H. A. 1987. Bestia, Tripterocladium, and Isothecium: an explication of relationships. Bryologist 90: 40--42. Shevock, J. R, D. H. Norris and A. J. Shaw. 2008. Identification, distribution and family placement of the pleurocarpous moss Bestia longipes (Sull. & Lesq.) Broth. Madroño 55: 291--296.


1. Bestia longipes (Sullivant & Lesquereux) Brotherus in A. Engler & K. A. E. Prantl, Nat. Pflanzenfam 1(3): 859. 1906     E F


Alsia longipes Sullivant & Lesqeureux, Musci Bot.-Amer. (ed. 2), 66. 1865; A. sullivantii Lesquereux ex Fleischer


Plants green to deep green, growing in rather pendulous wefts. Stems to 12 cm, pinnately branched with secondary branches to 1 cm; rhizoids rarely present, pale brown, smooth and essentially unbranched, inserted on stem base; axillary hairs 3-celled with 2 basal brown cells, only 4--5 \um wide at insertion but 10 \um wide distally, with the terminal cell hyaline and about 40 \um in length; pseudoparaphyllia about as broad as long, serrate at base, short cells throughout. Leaves to 1.6 mm, 3--5:1, symmetric and straight; margins narrowly recurved at least near mid leaf, decurrent at base; median cells smooth, 5--6 \um wide, 1.2--1.8:1, thick‑walled (lumen wall ratio 2--4: 1), not or inconspicuously porose; basal, juxtacostal cells somewhat more elongate, 3--4: 1; alar cells quadrate, thick-walled, with rounded lumina, extending more than 20 cells up the margins and extending inward to the basal plica, auriculate at the small decurrency; cells of apical region similar to median laminal cells, often prorate-spinose in a small patch near the costal apex; costa extending to within 10 cells of the apex, distal portion with many abaxial spines.  Perigonia nearly spherical on a short stalk, bud‑like with bracts broadly ovate, 1.2--1.4:1, mostly rather sparsely cloaking and inserted on the ventral side of the main axes; perichaetia on ventral side of main erect axes, the bracts 2--3 mm, ecostate or with a short costa, strongly convolute around the seta; inner perichaetial bracts with post-fertilization development abruptly acuminate from an elliptic base.  Seta straw-colored, rarely reddish tinged, to 1.5 cm, erect, sporophyte often shorter than adjacent lateral branches.  Capsule pale brown, not distorted or sulcate when dry; urn to 4 mm, 4--5:1;  operculum inclined-rostrate, about 1/5\x length of urn;  exostome to 500 \um, teeth long and very narrow with base only 50 \um wide, evenly contracted from base without a shoulder; outer surface of exostome horizontally to obliquely striate basally but becoming smooth to lightly papillose distally, pale yellow, erect when dry;  endostome smooth with segments shorter than the exostome, very narrow but perforate along mid-line, arising from a short basal membrane with cilia paired and appendiculate.  Spores smooth, 10--14 \um.


Forming large colonies over rock walls and boulders especially along streams, coastal mountains influenced by summer fog, infrequent on basal burls of broadleaf trees, especially (Umbellularia); moderate elevations; Calif.


Bestia longipes is usually recognized by the pattern of erect to decumbent, frondose branching.  The frondose branches have an elongate main axis with markedly shorter branch axes so there may be a 10:1 ratio of length to width.  Bestia longipes is infrequently collected with sporophytes, which may be difficult to see at first.  This is due to the fact that sporophytes initiate from perichaetia inserted on the ventral side of the decumbent main axis thereby seta elongation parallels the stem and substrate as opposed to being elevated. Additionally the sporophytes are not much longer than the closely associated ultimate branch axes. Bestia can be confused in the field only with Isothecium, especially hydrated plants when both occur mixed. Bestia can be readily distinguished by serrations only distally in the leaf, cells uniform throughout, generally 4:1, and costa prominent, extending to within 10 cells of the apex. In Isothecium, the serrations occur over a much larger portion of the leaf margin, the alar region is distinctly lighter colored compared to the remainder of the lamina, and juxtacostal cells approach 8:1.


2. ISOTHECIUM Brid., Bryol. Univ. 2: 255.  1829 * [Greek isos, equal, and theke, capsule, alluding to symmentric capsule]

W. B. Schofield†


Plants slender, in often dense, pendent wefts. Stems creeping, irregularly branched, bearing distant broadly triangular, 1-costate or ecostate weakly toothed decurrent leaves and blunt foliose to deltoid pseudoparaphyllia; secondary branches often dendroid and regularly or irregularly branched, these sometimes producing flagelliferous terminal shoots with reduced leaves. Primary stem leaves similar to those of the branchlets, erect-spreading to strongly imbricate, occasionally wide-spreading, dark green to brownish green, occasionally yellow-green to bronze, somewhat glossy. Branchlet leaves ovate to ovate-lanceolate, coarsely toothed, especially in apex, margins plane to slightly undulate; costa single, often ending in a spine abaxially; leaf cells smooth or prorulose abaxially, usually hexagonal to elongate in most of lamina; alar cells in a well-defined, sometimes excavate group of smaller shorter cells, varying in number, often grading into adjacent elongate cells.  Seta elongate, red-brown, smooth, 1--3 cm. Capsule cylindric, rarely erect, mostly suberect or inclined, 1.5--3 mm; operculum conic; peristome double, yellow. Calyptra naked or sparsely hairy.


Species 11 (5 in the flora): Northern Hemisphere in mainly temperate to subtropical climates, Atlantic and Pacific North America, Europe, Asia.


SELECTED REFERENCES: Allen, B. H. 1982. Isothecium alopecuroides new to North America.  Bryologist 85: 421--423.  Allen, B. H. 1983. Isothcium myosuroides Brid., and I. stoloniferum Brid., a quantitative study.  Bryologist 86: 358--364.   Allen, B. H. and A. Whittemore.  1996. Note on Isothecium myosuroides and I. obtusatulum (Musci: Brachytheciaccae) in western North America.  Evansia 13: 116--119.   Ryall, K., J. Whitton, W. B. Schofield, S. Ellis and A. J. Shaw.  2005. Molecular phylogenetic study of interspecific variation in the moss Isothecium (Brachytheciaceae).  Systematic Botany 30: 242--247.  2005.


1. Secondary stem system irregularly branched, strongly julaceous when dry; leaves with extensive triangular region of alar cells extending to 1/3\x leaf length  . . .  3. Isothecium cristatum

1. Secondary stem system irregularly or regularly branched, not julaceous, or if julaceous regularly branched, sometimes dendroid; leaves with reduced (sometimes excavate) region of alar cells extending less than 1/10\x leaf length.

2. Plants robust, 3--15 cm, secondary system often markedly dendroid and with pronounced stipe, rarely producing tertiary flagelliferous branches, irregularly branched . . . 2. Isothecium cardotii

2. Plants medium-sized, usually 3--9 cm, less differentiated, often producing attenuate tertiary branches, sometimes closely pinnate-branched.

3. Secondary systems pinnate, julaceous, glossy . . .  5. Isothecium stoloniferum (in part)

3. Secondary systems pinnate or irregularly branched, not strongly glossy       .

4. Secondary systems often pinnate, often producing extensive flagelliform branches . . . 5. I. stoloniferum (in part)

4. Secondary systems irregularly branched, not producing flagelliform branches.

5. Branch leaves of secondary system blunt, with few teeth, shoots julaceous . . . 1. Isothecium alopecuroides

5. Branch leaves of secondary system long-acuminate, sharply toothed, julaceous or not.

6. Branches of secondary system blunt, but leaves acuminate; julaceous . . . 5. Isothecium stoloniferum (in part)

6. Branches of secondary system sharp-tipped, leaves acuminate and erect-spreading or wide-spreading, not julaceous  . . . .4. Isothecium myosuroides


1. Isothecium alopecuroides (Lamark ex Dubois) Isoviita, Ann. Bot. Fenn. 18: 202.  1981


 Hypnum alopecuroides Lamarck ex Dubois, Méth. Éprouv., 228. 1803; Isothecium myurum Bridel ex Amann


Plants robust, yellowish to brownish green, with secondary stems somewhat pendent, irregularly branched, 1--5 cm, stipe short or not evident, the branches of equal length (1--2 cm).  Stems irregularly branched. Primary stem leaves distant, small, broadly to narrowly triangular, squarrose, with attenuate and sometimes secund apex; costa short or ecostate; margins weakly or not toothed; alar cells weakly differentiated; pseudoparaphyllia scarce, foliose, pointed or blunt. Branchlet leaves of secondary system ovate to ovate-lanceolate, 2--3 cm, imbricate to subjulaceous when dry; cucullate, costate to 2/3\x leaf length, tapering abruptly to blunt, slightly toothed apex, otherwise with entire margins; cells smooth, 7--12:1 in most of lamina, shorter and rhomboid at apex; alar cells pigmented, rounded to 4--6-sided, in an often excavate group confined to base just distal to marginal insertion.  Seta 0.8--1.2 cm. Capsule erect, 2--2.4 mm.


Rock; moderate elevations; Nfld.; Ont.; Europe.


The description of Isothecium alopecuroides is based on European specimens.  It has been reported from Newfoundland by B. H. Allen (1983). The specimen from Ontario is from Thunder Bay, collected by I. Brodo. It is scant and poorly developed, consisting of short secondary shoots. It was correctly identified by R. R. Ireland and B. H. Allen and reported by the latter (B. H. Allen 1982).  Able collectors have explored the two areas but have not rediscovered it.  It is a phytogeographic puzzle and unlikely to have been introduced through human activity.  Further collections are needed to demonstrate that it survives.  Its presence in North America seems doubtful.


2. Isothecium cardotii Kindberg in Macoun & Kindberg, Bull. Torrey Bot. Club 17: 278. 1890 E  F


Plants robust, dark green or yellow to golden green, secondary system often forming extensive slightly glossy mats, 3--15 cm. Stems creeping, irregularly branched; secondary stems rigid or soft, red-brown, usually stipitate, the stipe bearing distant leaves resembling those of primary systems, producing a frond-like pinnate branch-system (sometimes plumose), or irregularly branched, resulting in a somewhat dendroid system, arching downward when dry, sometimes flat dendroid and erect from substratum when humid, lateral branches not flagelliform; pseudoparaphyllia scarce, broadly foliose, blunt or with a few short teeth. Primary stem leaves small, broadly to narrowly triangular, often of colorless, distant squarrose leaves; margins entire to weakly toothed apex extending abruptly as an attenuate point, sometimes falcate; costa present or absent; alar region small, slightly decurrent with smaller, mainly truncate rectangular cells, extending into decurrency. Branchlet leaves ovate-lanceolate, tapering to long (sometimes twisted) acumen, margins coarsely toothed distally, basal margins nearly entire to weakly toothed; costa broad at base tapering toward apex, occasionally weakly forked, sometimes ending in an abaxial spine, extending to 2/3\x leaf length; alar cells in well-defined, sometimes excavate group of truncate, shorter, rectangular cells, extending ca. 1/3 distance across base but less than 1/10\x leaf length.  Seta 1--2 cm. Capsule inclined, 1.5--2 mm. 


Tree trunks, rocky cliffs and boulders; low and moderate elevations; B.C.; Alaska, Oreg., Wash.


Isothecium cardotii is clearly related to I. stoloniferum and can grow mixed with it, but is readily separated in size alone in most specimens, although occasionally specimens of I. stoloniferum are of similar size and this creates difficulties, but the presence of flagelliform branches favor I. stoloniferum.


3. Isothecium cristatum (Hampe) H. Robinson, Bryologist 65: 95.  1962  E


 Leptohymenium cristatum Hampe, Linnaea 30: 459. 1860;  Isothecium aggregatum (Mitten) A. Jaeger; I. brewerianum (Kindberg) Kindberg; I. howei Kindberg; I. hylocomioides (Kindberg) Kindberg


Plants medium-sized, dark green to brownish green. Stems irregularly branched, 1--5 cm, glossy, julaceous when dry, nearly of equal lengths with slight suggestion of a differentiated main stem except for a short stipe; branches curved downward when dry, attenuate at tips, with no tendency to produce flagelliform branches; pseudoparaphyllia foliose, deltoid, pointed. Primary stem leaves squarrose, broadly ovate, tapering abruptly to attenuate point (sometimes falcate); margins weakly toothed to nearly entire; costa weak or obscure and confined to leaf base; alar cells in well-differentiated triangular group to 1/4\x leaf length. Brachlet leaves ovate to ovate-lanceolate, 1.5--2 mm, plane, sometimes tapering abruptly to coarse-toothed apex; basal margins entire; costa slender; alar cells variable, usually a triangular area of shorter cells to 1/4\x leaf length, larger leaves of lateral branches gradually tapered and with more pronounced alar cells.  Seta 1--2 cm. Capsule erect to suberect, 1--2 mm. 


On trees and rocks, or logs, mainly in summer-dry-winter wet climates.


Endemic to western North America, from S.W. BC, Calif., Oreg., Wash.


Isothecium cristatum is a distinctive species with strongly julaceous shoots. The branch leaves of the secondary stems show a triangular area of alar cells most distinctly, which separates it from other species of the genus.  From Pterogonicum gracile, this feature as well as the single costa is immediately distinguishing. Antheridial plants have small bulbiform perigonia on main stem as well as lateral branches, and perichaetia are generally on main shoots


4. Isothecium myosuroides Bridel, Bryol. Univ. 2: 369.  1827


 Pseudisothecium myosuroides (Bridel) Grout


Plants yellowish to dark green, with creeping primary system, radiculose. Stems irregularly branched; secondary system forming soft mats of often proliferating, sometimes stipitate, arching shoots, 2--4 cm, stipes short to absent; branching irregular, sometimes close, with branch-system arching downward, frequently producing attenuate 2--5 cm flagelliform branches, with narrower smaller leaves; pseudoparaphyllia foliose, sometimes toothed, often blunt and broad, infrequent. Primary stem leaves distant, broadly or narrowly triangular, squarrose, sometimes secund with attenuate points, nearly entire; costa present or absent; alar cells barely differentiated. Branchlet leaves ovate to ovate-lanceolate, 1--1.5 mm; margins plane, toothed throughout, most strongly in attenuate apiculus; costa to 2/3\x leaf length; alar cells in well-defined small group at margin of leaf insertion, sometimes excavate, mainly of shorter cells than lamina, except in shoot decurrent portion.  Seta 1--2 cm. Capsule 1--1.5 mm.


Predominately rock, cliffs, boulders usually in shaded sites in forests, also occasionally epiphytic and at tree bases, mostly low to moderate elevations;  N.S., Nfld., P.E.I., Alaska, Calif.(?), Maine, N.H., N.C., Tenn.; Europe; n Africa; Atlantic Islands.


The eastern representation of Isothecium myosuroides is clearly the same as the European species, but the relationship of western North American material is unclear.  K. Ryall et al. (2005) supported this conclusion with molecular data, but the situation concerning some California specimens suggests that further analysis is necessary to clarify the identity of these specimens.  Isothecium myosuroides, although showing some variability, is far more uniform than I. stoloniforum and the infrequency of sporophytes in the former suggests that cloned populations are frequent. 


5. Isothecium stoloniferum Bridel, Bryol. Univ. 2: 371.  1827  E


Isothecium acuticuspis (Mitten) Macoun & Kindberg, I. brachycladon Kindberg, I. myurellum Kindberg, I. myuroides Kindberg, I. obtusatulum Kindberg, I. spiculiferum (Mitten) Macoun & Kindberg, I. thamnioides Kindberg


Plants dull to extremely glossy, brownish green, dark green, pale green to golden-green, occasionally bronze-brown, radiculose, with rhizoids in tufts. Stems irregularly branched; secondary branch system often acutely pinnate, elongate, 2--9 cm, with short stipe-bearing costate leaves smaller and more abruptly tapering to the toothed apex than those of tertiary branches, sometimes irregularly branched, these often producing flagelliform tips to 5 cm and with smaller, more distant leaves with alar cells weakly differentiated; pseudoparaphyllia foliose, blunt or deltoid, blunt or toothed. Primary stem leaves variable in orientation, generally erect-spreading, but occasionally widely divergent or strongly imbricate, distant, broadly triangular, squarrose with attenuate tips and nearly entire margins; costa present or absent; alar cells in small group at base, not decurrent, isodiametric except in decurrent portion, where elongate.  Branchlet leaves lanceolate to ovate-lanceolate or ovate, usually long-attenuate to a narrow acumen; margins coarsely toothed throughout; costa single, often ending in a spine; leaf cells smooth (sometimes prorulose abaxially), elongate; alar region confined to base near margin just distal to insertion, often excavate, of mainly isodiametric cells, except those at insertion where rectangular.  Seta 1--1.5 cm.  Capsule 1.5--2 mm.


Epiphytic on tree trunks and branches, occasionally on shrubs, exposed or shaded rock cliffs, boulder slopes, forests or open sites; low to moderate elevations (0--1500 m); Alta., B.C.; Alaska, Calif., Idaho, Mont., Oreg.


Isothecium stoloniferum is an extremely variable species strongly related to the less variable  I. myosuroides. There are populations impossible to distinguish from the latter species on morphological grounds.  It does differ, however, in its genetic composition (K. Ryall et al. 2005).  N. C. Kindberg, in particular, described many new species to accommodate variant populations, but his types are often difficult to apply.  There is a morphotype of I. stoloniferum that resembles I. alopecuroides in size and appearance but the leaves are not cucullate and the apex is acute and strongly toothed.  This appears to be most frequent along streams, either on boulders or outcrops in and beside the stream and often in well-drained but humid sites.  Occasionally it is epiphytic on tree trunks.  It does not produce attenuate flagelliform shoots on branches. On boulder slopes, always in exposed sites, a pinnate morphotype is frequent, and it is also on trees in similarly exposed surfaces.  This is julaceous but on the same tree or boulder some adjacent parts of the probable clone are characteristic of typical I. stoloniferum, but are not julaceous or bronzed or even reddish.  These two morphs are readily distinguished from I. cristatum where the extensive area of alar cells contrasts strongly with the reduced number in all morphs of I. stoloniferum.


A third morphotype is the predominant one of I. stoloniferum.  It has pinnate, acute-branched plants, sometimes with a stipe emerging from the primary system, or proliferating from the secondary system.  This can appear dendroid, especially when humid.  The shoots are not julaceous and flagelliferous branches are infrequent.  It has a tendency to produce short stolons adventitiously usually near the base of the stipe. A fourth morphotype mimics I. myosuroides and is often impossible to distinguish from it.  This morphotype is commonly epiphytic, has a strong tendency to produce flagelliferous branches and some populations can be composed entirely of flagelliferous branches.  Although the alar cells are less pronounced in this morph, the long-acuminate, strongly toothed leaves are characteristic.  It seems most practical to treat this as part of I. stoloniferum, and not as I. myosuroides; populations are scattered throughout the range of I. stoloniferum and, although “key” characters would not place it there, most specimens could be distinguished from I. myosuroides based on a suite of features.


In considering the I. stoloniferum complex, it is strongly suggested that I. myosuroides was derived from it as a more impoverished manifestation of more limited variability.  In the Aleutians, for example, an entirely vegetative morphotype fits into I. myosuroides and may represent a clone; sporophytes are unknown in all populations there. Antheridial plants have numerous bulbiform perigonia in secondary branch system as well as branchlets, and are usually paler and smaller than adjacent leaves. Archegoniate plants with perichaetia are generally on the main shoot of the secondary system.  In summary, this complex would profit from detailed study, both in the field and laboratory. 



3. TRIPTEROCLADIUM A. Jaeger, Ber. Thätik. St. Gallischen Naturwiss. Ges. 1877--78: 484. 1880 * [Greek tri, three; pteron, wing; klados, branch; alluding to perceived tripinnate branching]

Howard A. Crum†

Plants rather small, shiny. Stems irregularly 1(--2)-pinnate, the branches of unequal length; pseudoparaphyllia broadly rounded-foliose. Stem leaves oblong-ovate, broadly acuminate, decurrent; margins plane or somewhat recurved near the base, entire or ± serrulate; costa short and double to single and sometimes extending nearly to mid leaf; distal cells linear, thick-walled, smooth; alar cells small and subquadrate in rather sizable groups. Branch leaves smaller, more broadly acuminate, irregularly serrate distally. Perichaetial leaves pale, sheathing at base, abruptly short-subulate, entire or nearly so. Seta red, smooth. Capsule suberect and ± curved to horizontal; annulus well differentiated; operculum conic; stomata in the short neck; exostome teeth pale yellow, cross-striolate below; endostome a high basal membrane with narrow, densely papillose segments perforate along the keel, cilia single, nodose. Calyptra not seen.


Species 1 (1 in the flora): w North America.


Tripterocladium is a unispecific genus in the past moved in and out of  the Lembophyllaceae, but molecular data confirm its position in the family as closely related to Bestia.


SELECTED REFERENCES Crum, H. A. 1987. Bestia, Tripterocladium, and Isothecium: an explication of relationships. Bryologist 90: 40--42.


1. Tripterocladium leucocladulum (Müller Hal.) A. Jaeger, Ber. St. Gallischen Naturwiss. Ges. 1877--78: 484. 1880  E F


Hypnum leucocladulum Müller Hal., Flora 58: 79. 1875


Plants slender, pale yellow, green, or brownish. Stems erect-ascending, often filiform. Leaves of stem imbricate when dry, erect-spreading when moist, 1.1--1.2 mm; costa short and double or single and extending nearly to mid leaf; distal cells linear, thick-walled, smooth; alar cells small and subquadrate in rather sizable groups; leaves of branches 0.4--0.8 mm. Seta 1--1.5 cm. Capsules 1.5--2 mm. Spores papillose, 12--19 \um.


Dry, shaded cliffs and boulders; B. C.; Calif., Idaho, Oreg., Wash.