BFNA Title: Taxithelium
Taxithelium – Sematophyllaceae
W. B. Schofield†
XX. TAXITHELIUM Spruce ex Mitten, J. Linn. Soc. Bot. 12: 21, 496 1869 * [Greek taksi, order, and thele, nipple, alluding to single row of papillae over cell lumens]
Plants slender to medium-sized, in thin to dense creeping mats, dull yellow-green to brownish. Stems 1--3 cm, creeping, irregularly to regularly pinnate. Branches usually short, 0.2--2 cm, usually complanate foliate, sometimes with spreading lateral leaves and dorsal and ventral leaves smaller and appressed, contracted at clasping base. Stem leaves narrowly to broadly ovate to ovate-lanceolate, apex blunt, acute or acuminate, margins entire or weakly to sharply toothed, teeth often in pairs; costa short and double or absent; laminal cells rhomboid to linear, strongly to faintly 1-seriate papillose over lumen, occasionally smooth; alar region usually differentiated with somewhat elongate, sometimes inflated proximal cells, hyaline or colored, supra alar cells few to many, subquadrate, in 1--2 rows, often with 1 row extending up margin. Branch leaves similar to stem leaves. Specialized asexual reproduction rare, by filamentous gemmae. Sexual condition autoicous or dioicous; perichaetia and perigonia on stems or bases of branches. Seta elongate, smooth. Capsule ovoid, inclined to horizontal; exothecial cells not or weakly collenchymatous; peristome double, exostome and endostome teeth of equal length, alternate; exostome of 16 subulate striolate teeth, endostome with medium to high basal membrane, cilia 1--3, appendiculate; operculum conic with short or long rostrum. Calyptra smooth, cucullate. Spores spherical, 12--22 \um, smooth to finely papillose.
40 (1 in the flora): tropical and subtropical. North America, South America,
Central America, Asia, Africa,
Taxithelium occurs mainly in forests, generally as corticolous on tree trunks and branches, but also on logs, occasionally on rock and soil.
REFERENCES: Buck W. R. 1985. A review of Taxithelium (Sematophyllaceae) in
1. Taxithelium planum (Bridel) Mitten, J. Linn. Soc. Bot. 12: 496. 1869
Hypnum planum Bridel, Muscol. Recent., Suppl. 2: 97. 1812
Plants slender. Stems usually less than 10 cm, yellow-green, somewhat glossy, subpinnately branched. Leaves short-acuminate; alar cells differentiated but without row of inflated, elongate cells; leaf cells smooth or 1-seriately multipapillose. Sexual condition autoicous.
Bark of trees and on exposed roots and rotten logs; Fla.; Mexico; West Indies; Central America; South America; Asia; Africa; Australia.