BFNA Title: Clasmatodon
Author: D. H. Vitt
Date: October 9, 2009
August 3, 2010
Edit Level: R2
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden
BFNA Web site:


Return to Home

XX.  CLASMATODON Wilson, Kew. J. Bot. 4: 421.  1842.

Dale H. Vitt


Plants small, slender, dull to bright green, in loosely interwoven, straggly mats.  Stems prostrate, creeping, and irregularly branched; branch foliage similar to that of stem; axillary hairs 4--6-celled, distal cell obtuse, pale brown; juvenile branch leaves narrowly acute.  Stem leaves ovate to ovate-lanceolate, acute to narrowly obtuse, concave, imbricate and ± subsecund, little decurrent; margins entire, subentire, to serrulate in distal 1/2, costa slender, reaching 1/3--2/3\x leaf length, ending without a spine; basal laminal cells quadrate to subquadrate, shorter at margins, in many rows, walls thin; laminal cells rhombic to oblong-rhombic, thin-walled, smooth.  Branch leaves similar to stem leaves.  Sexual condition autoicous; perichaetial leaves abruptly acuminate, erect to flexuose from sheathing base.  Seta reddish, smooth.  Capsule erect, narrowly elliptic to oblong, symmetric; annulus of 3--4 rows of small, brown cells, persistent; operculum long-rostrate; peristome double, of 16 short, slender, unequally 2-fid segments partially fused to inconspicuous basal membrane; exostome of 16, very short, blunt, partially fused teeth.  Calyptra naked.  Spores 14--21 \um, finely roughened.


Species 1 (1 in the flora): North America, Europe.


Clasmatodon has been variously placed in the Fabroniaceae or the Myriniaceae, but molecular data strongly suggest a position in the Brachytheciaceae as a small, epiphytic, monotypic genus with a reduced peristome.


1. Clasmatodon parvulus (Hampe) Sullivant in A. Gray, Man. Bot. No. U.S., ed. 2, 600.  1856


Leskea parvula Hampe, Linnaea 13: 46.  1839; Clasmatodon parvulus var. rupestris Lesquereux & James


Stems to 1(--2) cm, branches to 2(--5) mm.  Stem leaves 0.4--0.7 x 0.3--0.5 mm; mid-leaf cells 18--30 X 8 --10 \um.  Seta 2--5 mm.  Capsule 0.7--1 mm.


Tree trunks and bases of trees, often in flood plain forests, or more rarely on calcareous rocks; 0--400 m; Ala., Ark., Fl., Ga., Ill., Ind., Ky., La., Md., Miss., Mo., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va.


Clasmatodon parvulus is an inconspicuous moss forming small, slender, straggly mats on tree trunks in the southestern U.S.  In this habitat, it is characterized by a short costa (Leskea species have a strong costa ending near the apex), ovate, mostly bluntly acute leaves (Lindbergia has long-acuminate leaves), and the lack of erect, flagelliform branchlets (as in Platygyrium repens).  The narrowly elliptic, erect capsules, with very reduced peristomes, on short setae are also diagnostic.