BRACHYTHECIUM. 401 



entire, rarely superficially denticulate at apex, nerve reaching to 

 the middle ; cells variable in width, linear-rhomboid, usually 

 8-10 times as long as broad, pellucid, much laxer towards base, at 

 angles sub-quadrate, somewhat opaque, forming a narrow but 

 rather long marginal band. Seta smooth. Capsule small, shortly 

 oval. Dioicous. 



Hab. Stony places, wall-tops, etc., on siliceous soil ; common. Fr. very rare, 

 spring. 



A more slender plant than either the preceding or B. salebromm ; usually readily 

 known by the julaceous imbrication of the leaves, which are more abruptly acuminate, 

 almost always entire, of thin texture and sometimes almost hyaline. B. glareosum 

 at times somewhat simulates it, but may then be known by the more gradually and 

 more longly acuminate, denticulate leaves. 



4. Brachythecium salebrosum B. & S. {Hypnum salebrosum 

 Hoffm. ; Hypnum plumosum L., non Swartz.) (Tab. LII. I.). 



Intermediate in habit and vegetative structure between B. 

 rutabulum and B. glareosum, and, like the former, very variable. 

 The leaves are usually narrower than in typical B. rutabulum, 

 somewhat deltoid-lanceolate, gradually tapering to a rather long, 

 fine acumen, but not so long as in B. glareosum, often sub- 

 secund, hardly concave, or somewhat concave-carinate at base, 

 more or less deeply plicate, denticulate all round, or almost entire, 

 margin plane or recurved ; nerve thin, reaching about half-way 

 or to the base of the acumen ; areolation as in B. rutabulum. 

 Seta smooth, usually rather long, but variable. Capsule oval- 

 oblong, somewhat turgid at back, curved ; annulus narrow. 

 Autoicous. 



Var. /3. palustre Schp. {Hypnum Mildeanum Schp.). More 

 robust and less branched, more erect, with larger, broader, 

 cordate-triangular leaves, erect, not sub-secund, more rigid, 

 hardly plicate, more shortly acuminate. 



Hab. About the roots of trees, the foot of rocks, on stones, etc. ; rare. The 

 var. 3 in damp clayey meadows, etc. ; rare. Fr. autumn. 



The essential characters of this species are the quite smooth seta, by which it is 

 distinguished from B. rutabulum and B. campestre, and the autoicous inflorescence, 

 separating it from B. glareosum and other dioicous species. It is also usually a more 

 silky plant than B. rutabulum, with narrower, more shining, more plicate leaves, 

 with longer acumens, though shorter than in B. glareosum. It is however a very 

 variable plant, and some forms approach B. rutabulum so closely that it is doubtful 

 whether barren plants may be always safely referred to one or the other, especially as 

 the paludal form of B. rutabulum, which most nearly approaches the present species 

 in its narrower, more acuminate leaves than in the type, is most frequently barren. 

 B. salebrosum is however, as Spruce pointed out, a very fertile species, the flowers 



AI 



