LESKEACEAE 73 



D. Leaves not bordered, serrate. 

 M. stellare Reich. "On shaded cliffs and banks and about 

 the roots of trees in swamps, rather frequent but rarely fertile," 

 Muse. App. 216; Palisades, N. Y., E. G. B., Bx! 



Subgroup. 2. Pleurocarpae 



Sporophyte from a lateral bud on a branching prostrate or 

 ascending plant; occasionally the plants are erect, as in Clima- 

 cium. Peristome for the most part almost like that in the Bry- 

 aceae, except that in the Hypnaceae and some closely allied 

 genera, the basal segments of the peristome teeth are orna- 

 mented by very fine transverse lines. 



Family 21. LESKEACEAE 



Mosses of varying habit and size, growing on shaded earth, 

 stones, trunks of trees, or decayed wood, usually lusterless; 

 main stems creeping with ascending or erect secondary stems. 

 In Thuidium the stems are regularly pinnately branched and 

 ascending, having somewhat the appearance of miniature ferns. 

 Stem leaves often very different from the branch leaves, both 

 strongly costate in most species, costa never excurrent; leaf cells 

 rarely more than three times as long as broad, often less, mostly 

 papillose, papillae often very large; leaf ceils of the basal por- 

 tion of the leaves more elongated and less strongly papillose, 

 often smooth. Paraphyllia present in most species, varying 

 in form but mostly slender and branched. Seta long, smooth, 

 twisted when dry. Capsule erect and symmetric in most of 

 our species, except in the genus Thuidium. Thuidium also has 

 the perfect hypnaceous peristome, but most of the other genera 

 illustrate well the degeneracy of the peristome in erect capsules, 

 in which the cilia are usually vestigial or lacking and the seg- 

 ments often very narrow, or, in some cases, imperfect. 



Key to the Genera 

 I — Plants regularly and pinnately branching, capsules usually curved 



with perfect peristomes. (See also Claopodium) Thuidium 



Secondary stems usually ascending from prostrate main stems, not 

 regularly pinnate; peristomes usually imperfect, and capsules 

 erect and symmetric 2 



