BFNA Title: Palamocladium
Author: M. S. Ignatov
Date: September 26, 2009
Edit Level: R
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden
BFNA Web site: http://www.mobot.org/plantscience/BFNA/bfnamenu.htm

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XX. Palamocladium Müller Hal., Flora 82: 465. 1896 * [Greek palama, palm leaves, and clados, branch, inappropriately alluding to spreading branching]

Michael S. Ignatov

Plants large, rigid, in moderately loose tufts, deep green to brownish or olive-green, somewhat glossy. Stems prostrate to ascending, with weak central strand, moderately to very densely terete-foliate, irregularly pinnately branched, branch foliage similar to that of stem; axillary hairs 3--6-celled; juvenile branch leaves acute. Stem leaves imbricate, erect, lanceolate-triangular to ovate-lanceolate or lanceolate, gradually tapered upwards and narrowly acute or somewhat acuminate, abruptly rounded to insertion, slightly auriculate proximally, deeply plicate or, in slender plants, smooth; margin coarsely serrate, with teeth partly recurved, costa vanishing shortly before apex or almost reaching it, lacking a terminal spine; juxtacostal basal cells short-ovate in 2--3 rows with strongly incrassate and pitted walls, elongate distally in 2--4 rows, with strongly pitted walls; leaf corner cells small, subquadrate, forming an opaque group of 10--15 x 5--8 cells, more or less clearly delimited; laminal cells elongate, relatively short, moderately thick-walled, moderately porose; cells in acumen rhombic. Branch leaves somewhat narrower and shorter than stem leaves, otherwise similar. Sexual condition dioicous or phyllodioicous; perichaetial leaves with reflexed acumens. Seta red-brown, smooth. Capsule erect; annulus separating by fragments; operculum high, gradually tapered to its rostrum; peristome hygrocastique; exostome teeth cross-striolate basally, pale yellow; endostome with basal membrane ca. 1/4 of its length, cilia absent. Calyptra naked. Spores 10--18 \um.

Species: 3 (1 in the flora): widespread in tropical to south temperate regions worldwide.

Palamocladium was included in Homalothecium by H. Robinson (1962), but this decision was not accepted by H. A. Crum and L. E. Anderson (1981) or by H. Hoffmann (1997). According to M. S. Ignatov and Huttunen (2002) these genera belong in different subfamilies.

SELECTED REFERENCE Hoffmann, H. 1997. A monograph of the genus Palamocladium (Brachytheciaceae, Musci). Lindbergia 22: 3--20.

1. Palamocaldium leskeoides (Hooker) E.G. Britton, Bull. Torrey Bot. Club 40: 673. 1913

Hookeria leskeoides Hooker, Musci Exot. 2 (Append.), 18. 1818

Stems to 3--7 cm, branches to 10 mm. Stem leaves 2.3--3 x 0.8--1 mm; costa 0.9--1\x leaf length; basal cells near costa 9--11 \um wide; cells adjacent to decurrency somewhat larger, alar cells smaller 6--10 x 7--11 \um almost to margins; mid-leaf cells 35--65 x 5\um.

Limestone cliffs and boulders; 0-900 m; Ga., N.C., Okla., Tenn., Tex., W.Va.; Mexico; West Indies; South America; e Asia; Africa.

Sporophytes of Palamocladium leskeoides have not been found in North America; their description follows H. Hoffmann (1997) and Asian specimens examined. This species can be recognized by narrow, rigid and, when well-developed, plicate leaves. Although these characters are the same as those of Homalothecium, Palamocladium superficially looks different, as its leaves are erect to somewhat spreading when dry whereas leaves are more appressed in Homalothecium. Also, the color of the plants is olive-brownish but richly golden in Homalothecium, and the luster of Palamocladium is rather “oily,” similar to that of Isothecium, but rather “silky” in Homalothecium. Microscopically, the coarse serration in the acumen is helpful in species recognition, as well as the extensive groups of small alar cells forming opaque areas. H. Hofmann (1997) accepted P. leskeoides in a broad sense. Based on morphology, it would probably be impossible to successfully split this highly variable species. Confirmation of its genetic unity based on molecular data, however, is necessary.

OTHER REFERENCES

Crum, H. A. and L. E. Anderson. 1981. Mosses of Eastern North America. 2 vols. New York.

Ignatov, M. S. and S. Huttunen 2002 [2003]. Brachytheciaceae (Bryophyta)---a family of sibling genera. Arctoa 11: 245--296.

Robinson, H. 1962. Generic revisions of North American Brachytheciaceae. Bryologist 65: 73--146.