BRACHYTHECIUM. 403 



papillose, robust, variable in length, usually about 1 inch ; capsule 

 of varying length, oval-oblong or sub-cylindrical, gibbous at back, 

 arcuate, dark reddish brown ; lid conical, short and obtuse or 

 longly acuminate ; annulus broad ; peristome large. Autoicous. 



Hab. On earth, walls, trees, etc. Very common. Fr. winter. 



With all its variations this is as a rule not a difficult plant to recognise, except 

 in those forms, when barren, which are mentioned above as somewhat approaching 

 B. salebrosum ; these are chiefly paludal. The rather coarse, broad, rigid leaves, 

 glossy or scariose but hardly silky, almost always more or less spreading even when 

 dry, give it a characteristic appearance. It is often found barren, but is quite common 

 in fruit, which it frequently produces in great profusion ; and the seta, rough through- 

 out all its length, at once identifies it ; all the other British species of the genus, 

 except B. rivulare, which have this character, being of quite different habit. B. 

 rivulare is dioicous, and is almost always known by its shortly and widely pointed, 

 decurrent leaves with very lax basal areolation and well defined auricles. B. sale- 

 brosum, B. campestre and B. glareosum have almost always narrower, silky leaves, 

 more deeply plicate and longly acuminate. B. Starkei has much shorter and wider 

 cells, strongly decurrent leaves, etc. ; B. velulinum is much more slender. 



Several varieties have been described, the var. longisetum B. & S. being one 

 of the most marked, having long stems with narrower more distant leaves, and much 

 longer setae ; but neither this nor others seem of great importance. The var. robustum 

 Schp. has erect, stout branches, with densely crowded, very wide leaves. Many 

 allied species have recently been described from N. America, but it seems probable 

 that some of them at least will have to rank as synonyms or as varieties ; the American 

 forms, indeed, of Brachythecium are very numerous, and a revision of this genus, 

 including the newly described forms, will soon become very desirable. 



An alpine form occurs in mountain streams with dense, parallel, slender branch- 

 ing, and small, ovate-oblong, tapering leaves. 



B. rutabulum is by far our commonest species, and very abundant. 



7. Brachythecium rivulare B. & S. (Hypnum rivulare 

 Bruch) (Tab. LII. L.). 



Resembling B. rutabulum and almost equally variable ; 

 robust, usually paler, often golden green, shining, more rigid, 

 with longer branches. Leaves more ere.ct and more regularly 

 imbricated when dry, those of the stems usually widely ovate- 

 triangular, shortly and rather widely, not finely acuminate, some- 

 times only sub-acute (those of the branches narrower and more 

 longly acuminate), concave, decurrent , rigid and sub-scariose, 

 more or less deeply plicate ; margin plane or slightly revolute at 

 base, denticulate ; upper cells as in B. rutabulum, or frequently 

 shorter and much laxer, the basal laxer, wide, usually with 

 incrassate, highly porose walls, at decurrent angles large, pellucid^ 

 forming rather well-defined, sometimes hyaline auricles, in the 

 older leaves frequently orange-brown. Seta strongly papillose ; 

 capsule usually rather short and turgid. Dioicous. 



Var. /3. latifolium Husn. (Hyp. latifoliumhindb.). Secondary 

 stems erect, slender, almost simple, cuspidate ; usually of a 



