Jennings: Manual of Mosses — 26. Leucodontaceae 183 



shoots: paraphyses few, filiform: plants more or less stiff and robust, laxly 

 cespitose, mostly shining; stem cylindric, central axis rudimentary or none; 

 main stem creeping, branched, radiculose with brownish radicles; secondary 

 stems numerous, erect or ascending, rarely pendent, thickly-leaved, simple or 

 branched; leaves pluri-seriate, decurrent, often plicate, ovate to lanceolate, 

 abruptly to slenderly acute, non-bordered, one layered; costa double or simple 

 or none; leaf-cells incrassate, mostly smooth, rhombic above, below elongate 

 along the middle of the leaf, towards the margin rounded-quadrate in many 

 series; capsule erect, symmetric, oval or ovate to oblong-cylindric; annulus pres- 

 ent; peristome double, teeth lanceolate to lance-subulate, densely articulate, 

 non-bordered, mostly papillose, mostly without projecting lamellae, rarely with 

 cross-striae on basal plates; basal membrane of inner peristome low, segments 

 rudimentary and narrow or none, as long or shorter than teeth, cilia none; lid 

 conic, obliquely rostrate; calyptra cucullate; spores medium to large. 



On rocks and trees, mainly confined to temperate regions; 7 genera; only 2 

 genera in our region. 



Key to the Genera 



A.Costa double or none 1. Leucodon 



A. Costa single 2. Leptodon 



1. Leucodon Schwaegrichen 



Dioicous: blackish to yellowish or brownish-green, dull or lustrous: pri- 

 mary stems very long and branched; secondary stems usually simple, equally 

 high, sometimes more or less pinnate, thickly leafy; leaves drying appressed, 

 straight or secund, mostly pluri-plicate, when moist spreading, ovate-acuminate 

 to short-acute, entire or apically serrate, ecostate; median leaf-cells smooth, ob- 

 long-rhombic, the basal reddish-yellow; inner perichaetial leaves high-sheathing, 

 long-acuminate: seta mostly more or less elongate, reddish; capsule mostly 

 exserted, oblong to oval (or globose), reddish brown to blackish, with a small 

 mouth and short collum, stomata none; annulus present; peristome double with 

 the inner peristome rudimentary or apparently lacking; teeth whitish to yel- 

 lowish, mostly gaping in the middle or divaricately cleft; lid conic, constricted 

 at the base, sometimes obliquely rostrate; calyptra smooth, cucullate, envelop- 

 ing the capsule and upper end of seta; spores .025-. 03 5 mm, yellowish-green, 

 finely warty. 



A widely distributed genus of about 30 species, occurring on trees and 

 rocks; 8 species reported for North America; 3 species, probably, in our region. 



Key to the Species 



A. Leaves plicate; secondary stems well developed: seta about 2-3.5 mm long, with cap- 

 sule emergent but shorter than the perichaetial leaves 1. L. brachypus 



A. Secondary stems less developed: capsule long-exserted B 



B. Leaves ovate-elliptic, rather abruptly and shortly acuminate, scarcely plicate 



2. L. julaceui 



B. Leaves lance-ovate, long and slenderly acuminate, much plicate 3. L. scitiroidcs 



