WEISIA. 213 



14- Weisia verticillata Brid. (Bryum verticillatum L. ; 



Mollia verticillata Lindb., Braithw. Br. M. Fl. ; Eucladium 



verticillatum B. & S., Schp. Syn.) (Tab. XXXI. G.Y 



Densely tufted, |-2 inches high, often encrusted with 

 calcareous matter ; pale glaucous green above, whitish below, 

 stems very slender, fragile, much branched. Leaves erecto- 

 patent, not much crowded, when dry appressed, hardly twisted, 

 long, linear-lanceolate or linear-subulate from a slightly broader 

 base, acute or apiculate ; margin plane, toothed just above the 

 base for a short distance ; nerve very broad, occupying most of 

 apex and excurrent in a mucro, or vanishing in the point ; cells at 

 base long, narrow (5-10 times as long as broad), thin-walled, 

 hyaline, above rounded-quadrate, obtusely papillose. Seta 

 reddish; capsule oval-oblong, thick-walled, peristomate ; lid 

 obliquely rostrate ; peristome teeth 16, orange, flat, oblique, 

 entire or divided. 



Hae. Wet limestone rocks, more rarely on sandstone. Not uncommon. Fruit 

 very rare, summer. 



Readily known by its glaucous colour, more slender stems, and narrower leaves ; 

 under the microscope the toothed basal margin is very characteristic and distinct. It 

 is sometimes so thickly crusted with calcareous matter as to be quite hard and stone- 

 like. 



43. TRICHOSTOMUM B. & S. emend. 



Plants for the most part tall and rather robust ; leaves 

 usually narrow and elongate, with lax, pellucid, or hyaline 

 basal cells, and minute, obscure, papillose upper areolahon, 

 curled and often strongly cirrate-incurved when dry. Capsule 

 oblong or cylindrical, peristomate, teeth slender, divided to or 

 nearly to the base into two filiform divisions, more or less 

 imperfect or long, erect, oblique or contorted. Dioicous. 



Although I have little doubt that Lindberg is right in 

 combining with the species usually included under Trichostomum 

 the plants belonging to the Section Tortella CM. \pi 

 Barbula), as truly congeneric, it is with more hesitation that I 

 have retained the generic name Trichostomum while including 

 species the peristome of which in its structure exactly contradicts 

 the definition of the genus as given by its . authors. It has 

 however always been admitted, even by the authors themselves, 

 that the genus as so defined is an unsatisfactory one, added to 

 which we have the fact that in some of the original species there 



