94 A MANUAL OF MOSSES 



5. TRICHOSTOMUM Hedwig. 



Dioicous, rarely autoicous : densely cespitose, medium size, 

 green to yellowish-green: stem with central strand, erect, 

 radiculose, rarely felted, densely leaved, mostly dichotomously 

 branching; leaves spreading, mostly crisped when dry, upper 

 leaves much the larger, long and narrow, more or less concave 

 to canaliculate, margins mostly erect to involute, often undu- 

 late, mostly entire ; costa well-developed, sometimes ending be- 

 low the apex or excurrent; upper leaf-cells small, rounded, 

 chlorophyllose, papillose on both faces, towards the base 

 elongated-rectangular, mostly hyaline : seta long, erect ; capsule 

 erect, rarely inclined, mostly symmetric, oblong-cylindric to 

 cylindric, short-necked, rarely strumose ; basal membrane of 

 peristome low or none, the teeth erect, smooth or papillose, red 

 or yellow, undivided or cleft into two filiform non-articulated 

 divisions which are sometimes approximate in pairs ; spore 

 small ; lid conic, rostrate, the exothecial cells of the base in 

 vertical series or rarely dextrorsely ascending; calj-ptra cucul- 

 late, smooth. 



A genus of about 100 species, widely distributed on earth 

 and rocks. About 20 species in North America ; only one in 

 our region. 



1. Trichostomum cylindricum (Bruch) C. Mueller. 

 (Didymodon cylindriciis Bryologia Europsa ; T. tenuirostre 

 Lindberg). 



(Plate XII) 



Rather loosely and softly cespitose, yellowish, dark be- 

 low: stems erect branching, rather flexuous, reaching to 1.5-2 

 cm. in height ; leaves about 2-3 mm. long, narrowly linear- 

 lanceolate, when dry crisped and contorted, when moist 

 spreading or flexuous, gradually acuminate or sometimes ratljer 

 abruptly narrowed to an acute apex, the margin papillose- 

 sinuate, plane or involute ; basal leaf-cells elongate-rectangular 

 or more or less angular-oblong, somewhat inflated, hyaline in 

 a broad band that does not extend up the margin, above rather 

 abruptly becoming much smaller, incrassate, quadrate to 

 rounded-hexagonal, the median and upper rounded-quadrate 

 to rounded-hexagonal or transversely oblong, densely papil- 

 lose, much incrassate; costa strong, usually forming the apex 

 of larger pellucid cells : seta single or sometimes in pairs, 

 slender, erect, about 1.5 mm. long, yellow; capsule linear- 

 cylindric, brownish ; lid conic and obliquely rostrate ; peris- 

 tome-teeth short, untwisted, linear-subulate, fragile, usually 

 more or less irregularly cleft or perforate ; spores mature in 

 autumn : dioicous : fruit produced but rarely. 



On wet non-calcareous stones in brooks or at the base 

 of cliffs in hilly or mountainous districts, in Europe, Asia,. 



