POLYTRICHUM. 43 



Hab. Summits of the higher Scotch mountains ; very rare. Ben Macdhui and 

 others of the Cairngorm range ; Ben Nevis ; Ben Lawers ; barren on the last named, 

 occasionally fertile on the others. Fr. late summer. 



A very rare plant with us, readily distinguished in the field by the short, obtusely 

 cucullate leaves with entire inflexed margins. P. strictiim and P. juniperinum differ 

 in the very acute, more or less aristate leaves. In P. sexangalare, although the 

 general outline of the leaf apex is obtuse, it will be found under the microscope that 

 the nerve is excurrent in a short mucro, which though rather blunt, gives a more acute 

 outline to the leaf than appears with the lens. The capsule, as is usually the case in 

 this section, becomes more inclined or even horizontal when old. The angles are 

 sometimes obscure. 



6. Polytrichum piliferum Schreb. (Tab. XI. A.) 



In loose tufts, glaucous green. Stems erect, simple, rarely 

 forked, i-i\ inches high, naked at base. Upper leaves rapidly 

 lengthening so as to form an elongate coma, when dry closely 

 appressed and straight, forming a narrow ovoid or clavate head. 

 Base of leaf narrower and longer than in the preceding species, 

 limb narrowly lanceolate, the wings broad/ inflexed upon the 

 front of the leaf and almost meeting, formed of narrow, trans- 

 versely elliptical cells, entire ; nerve reddish, at apex suddenly 

 becoming hyaline, and excurrent as a long, denticulate , hoary 

 arista ; apex of leaf, below the arista, somewhat muriculate, 

 smooth at back of nerve. Lamellae about jo, in section of 4-7 

 cells, the upper larger, elongate, broader in the middle, narrowed 

 above and below, so as to appear obtusely cruciform, not papillose. 

 Perichaetial bracts longer, the inner thin, whitish, without lamellae, 

 longly aristate. Seta i-i£ inches long; capsule covered by the 

 calyptra, erect, inclined when dry, small, shortly oblong, with 4 

 sharp angles, and occasionally an intermediate fainter one ; 

 apophysis distinct, short, constricted above, where it passes into 

 the capsule ; lid shortly and stoutly beaked, red or orange. Male 

 plants with shorter leaves, more shortly aristate. 



Hab. Dry heaths, common. Fr. summer. 



P. piliferum varies little, and may readily be known by the hoary leaf-points and 

 small capsule. An alpine form (Pol. Hoppei Hornsch. ) has shorter leaves, longer hair- 

 points, and shorter, broader capsules, on shorter pedicels. The cup-shaped male 

 inflorescence in this and the following allied species is bright red or orange, and forms 

 a conspicuous picture in the places where it grows. 



7. Polytrichum juniperinum Willd. (Tab. XI. D.) 



Stems scattered, taller than in the last species, 1-4 inches, 

 rarely branched, glaucous green, sometimes slightly tomentose at 

 base. Leaves less crowded at the top of the stems, spreading 



