46 POLYTRICHACE^E. 



nerve about 6-/0 times as long as broad; lamellae about 60-jo, 

 very low, in section of 3-5 cells, smooth, equal., rounded, or the 

 marginal one very slightly larger and a little longer than broad. 

 Perichastial bracts with long sheaths, longly acuminate. Seta 

 stout, long, 2-2i inches, rigid, orange below, paler above. Cap- 

 sule covered by the calyptra, erect or inclined, cernuous when 

 dry, oblong, with 5 or 6 (rarely 4) acute angles, yellow-green, 

 fawn-coloured when ripe, with a small but distinct apophysis, con- 

 tacted above where it joins the capsule ; lid large, with a rather 

 long beak ; mouth of the capsule wide, not contracted. 



Hab. Dry woods. Common. Fr. summer. 



A taller plant than the last, and often confused with P. commune ; it usually has 

 the leaves more crowded, and less squarrose when moist, and the beak of the lid 

 longer ; but the most certain character is to be found in the lamellse of the leaves, 

 which in the present species have the marginal cell smooth and rounded or oval (in 

 section), while that of P. commune is broad, depressed in the centre and bifid. The 

 perichaetial leaves are also more distinct in that species. P. ohioense R. & C. , is a 

 closely allied species from N. America, differing chiefly in the apical cells of the 

 lamelke more or less flattened, wider than long. The var. pallidisetum B. & S. 

 appears to be nothing more than a form with shorter stems and narrower, somewhat 

 elongated capsule. 



10. Polytrichum commune L. (Tab. XI. E.). 



Plants very tall, 6-18 inches high, in large, loose cushions, 

 deep green, tomentose at the base ; stems simple, rarely forked, 

 flexuose and wiry. Upper leaves very long, squarrose or re- 

 curved when moist, erect when dry and appressed, with the apex 

 flexuose ; rather laxly arranged, very long, from an oblong 

 sheathing base suddenly narrowed, limb lanceolate, gradually 

 narrowing from its base upwards, to a sharp dentate acumen ; 

 margin densely and sharply serrate to the base of limb, very 

 narrow, of about one row of small cells, similar to those of P. 

 formosum, as are also those of the leaf-base ; lamellae about 60, 

 low, thickened at«the upper border and channelled, appearing 

 in section of 4-6 cells, the marginal one broader, depressed in the 

 centre and bicuspidate. Perichaetial bracts more distinct, longly 

 sheathing, membranous, without lamellae, ending in an arista 

 formed by the excurrent nerve. Pedicel very long, 2^-4 inches, 

 stout. Calyptra descending below the capsule, large, golden 

 brown. Capsule at first erect, pale reddish brown when ripe, and 

 horizontal, four-angled, with the two lateral angles usually larger 

 and more prominent than the upper and lower, so that the capsule 

 is somewhat flattened ; in outline shortly rectangular or almost 

 cubic ; apophysis discoid, very distinct and narrowly constricted 



