EXPLANATION OF PLATE VII 



POLYTRICHUM 



Fig. I. P. commune var. perigoniale. 



Fig. la. Male plant of P. commune var. perigoniale showing the new 

 growth of the stem continued through the old male disk. 



Fig. lb. Calyptra covering capsule of P. commune var. perigoniale 

 enlarged. 



Fig. 2. P. piliferum. 



Fig. 2a. Leaf of P. piliferum, enlarged. 



Fig. 2b. Cross-section of leaf of P. piliferum showing lamellae and leaf- 

 margins folded in, enlarged. 



Fig. 3. Cross-section of leaf of P. commune showing lamellae and leaf- 

 margins not folded in, enlarged. 



Fig. 4. Peristome of Polytrichum, showing the membrane at the 

 mouth of the capsule joined at the edge to the tip of the teeth, 

 enlarged. 



Fig. 5. Capsule of P. commune, enlarged. 



Fig. 6. Capsule of P. jiiniperinum, enlarged. 



Fig. 7. Capsule of P. ohioense, enlarged. 



Fig. 8. Capsule of P. gracile, enlarged. 



Fig. 9. Capsule of P. alpinum var. arcticum, enlarged. 



