MOSSES WITH A HAND-I,ENS 23 



P. STRICTUM Banks will surely be found by all mountain 

 climbers. It is very common in open boggy places at an altitude 

 of 3,000 feet or more. It is closely related to P. Jumperinum, 

 but is readily distinguished by the more slender, densely radicu- 

 lose stems and the much smaller capsules. 



POGONATUM. 



The Pogonatums differ from the Hair-caps mainly in the 

 cylindrical capsules, not square or angular in section. The teeth 

 are thirty-two and the capsules are straight or curved. The 

 spores mature in autumn or winter, except in P. alpinum, in 

 which they mature about July. 



KEY. 



I. Stems branching ^. 



Stems simple; leaves numerous, strictly alpine, growing 



close together capillare. 



Stems simple; leaves few, radical; protonema persistent, 

 forming a green layer on which the plants are scat- 

 tered; plants of low and median altitudes 3. 



z. Plants dark green; capsules smooth, curved alpinum. 



Plants glaucous; capsules papillose, erect or very 



nearly so urnigerum. 



3. Leaves lanceolate-subulate, serrate brevicaule. 



Leaves Ungulate, blunt, entire brachyphyllum. 



P. BREVICAULE (Brid.) Beauv., the Slender Pogonatum, [P 

 tenue (Menz.) E. G. B.] is probably the most common of our 

 species. It grows on bare moist banks of clay or loam where 

 other plants have not yet obtained a foothold. The plants do not 

 grow close together, as with most mosses, but singly and scat- 

 tered, the soil between them being covered imth green felt-like 

 protonema. All mosses grow from just such green felt; but 

 after the moss plant proper has developed, the protonema usually 

 disappears. In P. brevicaule, however, the protonema is per- 

 sistent and plays an active part in the nutrition of the plant, 

 seeming to perform the function of leaves, for the leaves on this 

 plant are very few and short as compared with the allied species. 

 This is well illustrated by the figures, the dark shaded upper 

 portion of the leaf being the only part that contains chlorophyll 

 and therefore the only portion that performs the functions of a 

 leaf. These marked and interesting modifications may be due 

 to the fact that this moss grows on freshly disturbed earth, and 

 by this method is enabled to fruit before its competitors for the 

 space are able to develop The capsules mature in late autumn. 



