438 



POTTIACEAE. 



1. Weisia viridula (L.) Hedw. BRIGHT- 

 GREEN WEISIA. (Fig. 478.) Plants growing in 

 more or less crowded bright green tufts, up to 

 6" high; stems erect and simple or branched; 

 branches short; leaves crowded at the ends of 

 the branches, spreading, from an erect base, 

 points curled and twisted when dry, base 

 broader, apex with inrolled, entire margins, 

 forming a long sharp point; vein stout, excur- 

 rent into a short mucronate apex. Monoicous; 

 pedicel erect, slender, yellow or brown; capsule 

 small ovoid to cylindric, erect and symmetric or 

 slightly inclined; often dark brown and shin- 

 ing; calyptra cucullate; lid beaked; annulus 

 narrow, persistent; peristome inserted below the 

 mouth; teeth 16, short, papillose, often irregu- 

 larly split or perforate or short and unde- 

 veloped; spores rough, brown, maturing in 

 spring. 



On rocks at one station near Walsingham. A 

 common and variable species of wide distribution 

 in temperate regions. 



2. TKICHOSTOMUM Hedw. 



Plants medium-sized, usually growing crowded; stems erect, simple or 

 branched; leaves curled and twisted when dry, larger at base, with a narrow 

 sharp apex; margins flat or inrolled, entire; vein single, usually percurrent; 

 basal cells oblong and clear, upper cells denser, small and papillose on both 

 sides. Pedicel erect, elongate ; capsule erect, cylindric ; peristome single ; 

 teeth 16, either entire or divided to base, usually papillose; lid conic-beaked; 

 calyptra cucullate. [Greek, in reference to the narrow teeth.] Widely dis- 

 tributed in various temperate and tropical regions. Type species: Weisia 

 cylindrica Brueh. 



1. Trichostomum bermudanum Mitt. BERMUDA 

 TRICHOSTOMUM. (Fig. 479.) Plants in crowded bright 

 green or yellowish-green patches; stems up to 9" high, 

 usually simple; leaves crowded, curled and twdsted when 

 dry, base erect clasping, points narrower with the vein, 

 smooth and excurrent into a mucronate apex ; margins 

 entire, incurved above; basal cells lax with longer cells 

 on the margins extending up the blade to the papillose 

 cells of the upper part. Pedicel yellow, erect and 

 twisted ; capsule erect, cylindric, lid conic-beaked ; ca- 

 lyptra cucullate; peristome single, of 16 slender, papil- 

 lose, bifid teeth ; often disappearing and leaving only a 

 ragged membrane; spores large, rough, brown, maturing 

 in spring. 



Very common on walls, rocks and on the ground. En- 

 demic. Closely related to T. jamaicense Mitt. 



