Tropicos | Name - Phyllodrepaniaceae Crosby

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Phyllodrepaniaceae Crosby

African Plants, Senckenberg Photo Gallery

Project Name Data (Last Modified On 2/25/2011)

Acceptance : Accepted

Project data (Last Modified On 2/25/2011)

Discussion :

This small family of two genera, Mniomalia (2 species) and Phyllodrepanium (1 species), at first glance looks like a Fissidens. Indeed, the species of Phyllodrepanium was first described as a Fissidens. However, the obliquely inserted, complanate but inequilateral leaves and the uniquely derived terminal clusters of propagula distinguish it from other families.

Propagula in this family are principally borne in terminal clusters, although there are occasional propagula found in the stem leaf axils. A propagulum originates internally from a cell that forms a small “ochrea” (a term suggested by William Buck, in litt.) or collar proximally. The development of these propagula was described originally by Correns (1899). The stalks are persistent and indeterminate in growth. After a propagulum has abscised the stalk continues to grow giving rise to a new propagulum.

The phyllotaxy in this family is unusual. The leaves are four ranked, but these are arranged complanately on two sides of the stem with each side being two leaves thick, i.e., consisting of an upper and a lower row of leaves. The larger, concave parts of the leaves alternate dorso-ventrally and as a result the leaves on the upper rows are mirror images of the leaves on the lower rows.

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PHYLLODREPANIACEAE

Plants in loose horizontal swards or growing among other bryophytes. Stems unbranched or sparingly branched, reddish; rhizoids papillose, forming tomentum in lower parts of plants; outer 1–3 layers of cortical cells small, incrassate, usually pigmented; inner cortical cells larger, thin-walled, hyaline; central strand not differentiated; axillary hairs filiform, to 9 cells long, basal cell light tan or hyaline or all cells light tan. Leaves imbricate, inserted obliquely in four rows, complanate, appearing distichous, strongly inequilateral, each divided by the costa into a larger convex part and a smaller concave part, decurrent, keeled; margin elimbate or limbate; costa percurrent to short-excurrent, uniformly stereid band of few cells surrounded by a layer of substereid, chlorophyllose surface cells; cells unistratose, smooth or unipapillose, incrassate, porose or non-porose, usually rounded-quadrate, to linear-rhomboidal. Propagula in terminal clusters, olive-green to red-brown, stalked, multicellular, filiform, ochreate, subtended by smaller, more or less equilateral, spirally arranged leaves, frequently in leaf axils. Dioicous. Perigonia bud-like, axillary; perichaetia terminal, without paraphyses, perichaetial leaves longer than stem leaves, more or less equilateral, spirally arranged. Setae single, elongate, erect orange-red to castaneous. Capsules erect, radially symmetric or nearly so, more or less globose; exothecial cells quadrate to irregularly hexagonal with evenly thickened walls; stomata phaneroporous, long-pored, irregularly oriented; opercula small, conic; annuli not differentiated; peristome diplolepidous, exostome teeth 16, short, papillose, inserted below the mouth, endostome apparently absent. Spores smooth. Calyptrae cucullate, smooth.