TORTULA. I79 



■4. Tortula rigida Schrad. (Barbula rigida Schultz, Schp. 



Syn. ; Tortula stellata Lindb., Braithw. Br. M. Fl.) 



(Tab. XXVII. B.). 



Very small, but slightly larger than the last, in wider, brownish 

 patches. Leaves similar, but the upper rather larger, longer, and 

 narrower at the summit, more spreading ; nerve thick, vanishing 

 at apex, or, rarely, running out into a mucro or longer hair. Seta 

 longer, 3-3 lines, deep or brownish red ; capsule erect, narrowly 

 elliptical or shortly cylindrical, larger than in the last, lid longer, 

 usually fully half the length of the capsule, rostrate, straight or 

 slightly curved ; calyptra covering l A-}i capsule. Annulus broad, 

 separating; peristome longer, forming x\ turns of a spiral ; spores 

 as in that species. Dioicous ; male plants minute. 



Hab. Mud caps of walls in limestone districts. Not common. Fr. winter. 



T. rigida is recognisable without much difficulty from the last by the larger 

 capsule with longer lid, and the dioicous inflorescence ; T. ambigua has the capsules 

 distinctly longer, larger, and of a rather different texture, the peristome shorter, and 

 the calyptra hardly reaching below the lid ; the leaves are usually narrower and less' 

 obtuse than in the present plant, but not constantly so. 



Although the specific name rigida has, as Brahhwaite says, been applied at 

 one time or another to all the four species of this section, its use has been restricted to 

 the present plant for more than half a century, and its retention can hardly lead to 

 confusion at the present day. 



5. Tortula ambigua Angstr. (Barbula ambigua B. & S., 



Schp. Syn. ; Tortula ericsefolia Lindb., Braithw. Br. M. Fl.) 



(Tab. XXVII. C). 



Larger than the last in leaves and fruit ; in dense patches. 

 Leaves longer, Ungulate, incurved and cucullate at apex and 

 usually appearing obtuse, but slightly pointed when flattened out, 

 spreading, slightly curled when dry, smooth at back. Seta red, 

 paler above ; capsule erect, elongate-cylindrical , dark brown, of 

 rather thicker texture ; lid elongate ; annulus narrow, persistent ; 

 calyptra hardly reaching below the lid; peristome less strongly 

 contorted ; spores as in T. brevirostris. Dioicous. 



Hab. Mud-capped walls and banks in calcareous districts. Not uncommon, 

 and locally abundant. Fr. winter. 



The capsules in this species are distinctly cylindrical, not elliptic as in the last, 

 and the shorter calyptra will also serve to distinguish it. From the next it differs in 

 the erect capsules and the less acute leaves, which, though variable in this respect, are 

 rarely so short and obtuse as in T. rigida, and never so distinctly acute as in T. 

 aloides. 



