BFNA Title: Callicladium
Author: S. G. Newmaster 
Date: February 28, 2008
Edit Level: R 
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

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XX.  CALLICLADIUM H. A. Crum, Bryologist 74: 167. 1971 * [Greek calli, beautiful, and clad, branch or shoot]


S. G. Newmaster


Plants medium sized, in extensive flat mats, glossy, green, yellow-green to brownish.  Stems prostrate, irregularly to subpinnately branched (often horizontal), somewhat complanate, cortical cells small, thick-walled; rhizoids few, smooth, in clusters just proximal to leaf insertion; pseudoparaphyllia, foliose few.  Stem and branch leaves similar , erect or erect-spreading, concave, sometimes secund, ovate-lanceolate, acuminate, margins plane, entire, nondecurrent; costa short, double or occasionally lacking; cells moderately thick-walled, linear, smooth; basal cells pitted; alar cells enlarged, quadrate to rectangular, thick-walled, arranged in several differentiated rows of cells in concave, yellow-brown alar groups.  Specialized asexual reproduction lacking.  Sexual condition autoicous.  Perichaetial leaves differentiated, ovate-lanceolate, long-acuminate, smooth.  Seta orange-red, smooth. Capsule suberect or inclined; annulus slightly differentiated; operculum conic; peristome teeth orange-yellow; endostome papillose segments broad and keeled, not or narrowly perforated along the keel. Calyptra cucullate, smooth. 


Species 1: circumtemperate and circumboreal.


Callicladium is a monotypic genus distinguished by the slightly flattened, tapered branches, crowded, concave leaves with a small double costa, and suberect and only slightly curved capsules. Early associations with the genus Hypnum were supported by typical hypnaceous characters: curved inclined capsules, terete branches with falcate-secund, and often serrate leaves. The genus Heterophyllium has been long associated with but differs from Callicladium in its pinnate branching, and differentiated stem and branch leaves that are strongly serrate. H. A. Crum (1971) appropriately chose the name for the new genus Callicladium to emphasize the distinctively flattened and tapered "pretty branches."


SELECTED REFERENCE:  Crum, H. A. 1971. Nomenclatural changes in the Musci. Bryologist. 74: 165--174.


1. Callicladium haldanianum (Greville) H. A. Crum, Bryologist 74: 167. 1971


Hypnum haldanianum Greville, Ann. Lyceum Nat. Hist. New York 1: 275, fig. 23. 1825; Heterophyllium haldanianum (Greville) Fleischer


Stems to 3--8 cm.  Leaves 1--2 x 0.5--0.8 mm, crowded, upturned-homomallous particularly near the ends of branches, scarcely altered on drying; median cells 55--95 x 5--8 \um.  Seta 1.5--3.2 cm, flexuose.  Capsule 1.7--3 mm, reddish orange-brown, contracted below mouth, slightly wrinkled when dry.  Spores yellow, minutely papillose, 10--18 \um.


Common on logs and stumps in conifer and hardwood forests, occasional at the base of trees, soil, rock, in forests; low to moderate elevations; B.C., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que.; Ariz., Conn., Del., Idaho, Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Vt., Va., W.Va., Wis.; Europe; Asia.


Callicladium haldanianum grows in flat or loose extensive mats that are usually devoid of other species. It is distinguished by its concave leaves, short double costa, curved nearly erect capsules, and “the short tapered somewhat flattened branches resemble small swords” (H. A. Crum 1971).