WEBERA. 309 



*7. Webera commutata Schp. (Pohlia commutata Lindb., 

 Braithw. Br. M. Fl.) (Tab. XLII. D.). 



Closely allied to W. Ludwigii, but differing in the colour, 

 not reddish below, but either pale brown or blackish, dull pale 

 green above or glossy : slender, with elongated barren shoots, 

 the leaves small, widely oval, short and shortly pointed or sub- 

 obtuse, when dry closely incurved and imbricated, giving a 

 catenulate appearance to the stems; not or very slightly 

 decurrent ; margin plane or very slightly recurved ; nerve very 

 strong and thick, vanishing below apex ; cells a little narrower, 

 but wider in proportion to their length, than in W. nutans. 

 Capsule sub-pendulous, oval-pyriform with a tapering neck ; lid 

 •conical, apiculate. Dioicous. 



Var. p. catenulata (Bryum catenulatum Schp.). More 

 robust, rigid; leaves larger, when dry rigidly incurved and 

 turned to one side, giving the stem a slightly spiral, strongly 

 catenulate appearance. 



Hab. Rocks on high mountains, rare. The var.. /3, Ben Lawers. Fr. late 



summer. 



This is certainly distinct from W. Ludwigii, not only in the colour, which 

 exhibits nothing of the vinous red tint of that species, but also in the leaves, which are 

 usually smaller, and not or hardly at all decurrent, and in the nerve which is very stout, 

 especially in the lower part of the leaf. It varies considerably ; an elongate, slender 

 form with rather wider, more loosely areolated leaves being the Bryum filum of 

 Schimper, Synopsis Ed. II. The var. catenulata has especially marked the rigid, 

 •chain-like appearance of stem which is characteristic of the species ; alpine forms of 

 W. nutans and W. cucullata. come nearest it in appearance, but have longer and in 

 proportion nai rower cells, and thinner nerve, the latter plant also having the leaf-apex 

 more incurved and cucullate. W. commutata fruits more freely than W. Ludwigii. 



* Webera gracilis De Not. (Bryum gracile Schleich. ; Pohlia 

 gracilis Lindb., Braithw. Br. M. Fl.) (Tab. XLII. E.). 



Differs from W. commutata in the more rigid stems and 

 barren innovations, with narrower leaves which are straight and 

 appressed to the stem, not incurved and catenulate when dry ; and 

 in the capsule, which is very short and small, with a much 

 shorter neck, ovate or turgidly oblong-pyriform. 



Hab. Alpine rocks and sandy places ; very rare. Ben Lomond, sterile 

 (Stirton). Sands of Barrie (Forbes). Fr. late summer. 



This has a different habit and different capsule from W. commutata ; but it is 

 undoubtedly closely allied to it, and the characteristic growth and habit may be 

 occasionally seen in that species ; I have thought it therefore more satisfactory to con- 

 sider it a sub-species of W. commutata. The seta is frequently very strongly twisted 

 or looped at the summit when dry, so as to bring the capsule from a pendulous into a 

 horizontal position. 



