BFNA Title: Acroporium
Author: W. B. Schofield
Date: November 16, 2009
Edit Level: R
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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Acroporium – Sematophyllaceae

W. B. Schofield†

XX. ACROPORIUM Mitten, J. Linn. Soc. Bot. 10: 182. 1868 * [Greek acro, top, and poros, pore, possibly alluding the tubulose points of the branches]


Plants slender to robust, with leafy shoots 0.5--6 mm in diameter, in creeping to suberect yellowish to golden yellow mats. Stems 1--10 cm, irregularly to regularly pinnately branched, sometimes simple, with main stem and branches often arching upward to form a turf-like or loose mat; branch and stem tips often with a penicillate group of abruptly imbricate leaves. Leaves of main stem and branches similar, imbricate or strongly divergent, sometimes somewhat falcate, narrowly to broadly ovate-lanceolate, 0.5--4.0 mm, acute to acuminate with distal margins incurved to form a tubulose apex; costa double or absent; leaf cells smooth or rarely 1-papillose; alar cells 3--5 in 1 row, inflated, often colored, elongate with associated short cells distally.  Specialized asexual reproduction rare, by filamentous gemmae.  Sexual condition synoicous, autoicous, dioicous or phyllodioicous; perigonia on branches; perichaetia on stems or branches. Seta red, papillose or smooth, 0.5--2 cm. Capsule erect to inclined (occasionally nodding), ovoid to cylindric, exothecial cells collenchymatous, operculum finely rostrate from conic base; exostome of 16 lanceolate, finely striate and longitudinally furrowed teeth; endostome segments from wide basal membrane, equal to the length of exostome teeth, cilia single, short, occasionally rudimentary.  Calyptra cucullate, smooth. Spores spherical, smooth to finely papillose. 


Species about 60 (1 in the flora); tropical and subtropical, predominantly Indo-Malesian;  se North America, Central America, South America, Asia, Africa, Australia, Pacific Islands.


Acroporium occurs predominantly on logs, occasionally epiphytic at tree trunk bases, particularly in forested sites.


SELECTED REFERENCES: Crum, H.A. and L.E. Anderson. 1960. A bryological contribution from Florida. Bryologist 63: 43--45.


1. Acroporium smallii (Williams) H. A. Crum & L. E. Anderson, Bryologist 63: 42. 1960


Sematophyllum smallii Williams, Bryologist 23: 76. 1920


Plants small and delicate, in pale green to golden glossy creeping mats. Stems ca. 1 cm, leafy branches 0.4--0.6 x 0.7--1 mm.  Leaves 0.5--0.7 mm, median leaf cells narrowly rhomboid to linear, alar cells without apparent supra-alar cells.  Sexual condition autoicous.  Seta 4--7 mm, smooth. Capsule urn 0.4--0.6 mm, erect to inclined, annulus absent.  Spores spherical, slightly roughened, 13--14 \um.


Rotten logs, tree bark or charred wood, in moist live-oak hammocks.  Confined to Dade Co., Florida.


Distinctive gametophytic traits of Acroporium smallii include the long-ovate leaves with erect margins, linear medial cells, and alar cells much inflated and sharply differentiated from more distal cells.