THE FERN BULLETIN 



27 



are restricted to damp and shady places such as ravines 

 and forests. They are commonly found growing on 

 the trunks of trees, rocks and the like and in many 

 ways remind one of the mosses with which they are us- 

 ually associated. In view of these conditions, there- 

 fore, it is somewhat surprising to learn that some filmy 

 ferns, like a few mosses, are able to live in regions 

 where the supply of moisture is extremely limited. One 

 of these is the round-leaved filmy fern (Trichomanes 

 reniforme) which in New Zealand has been found 

 growing plentifully upon dry lava rock. Another spe- 

 cies Hymenophyllum sanguinolentum, which grows 

 with it is usually found in dryish woods, but the round- 

 leavecl filmy grows elsew T here in the wettest forests. In 

 the exposed situations on lava rock the fern avoids 

 some evaporation by rolling it fronds, but this cannot 

 prevent almost complete drying out. Possibly it has 

 something of the moss constitution which on occasion 

 can endure almost complete clessication. Trichomanes 

 reniforme is remarkable among filmy ferns for having 

 fronds that are four cells thick. 



The Bracken as a Weed. — Those who have oc- 

 casion to cross the half wild pastures and bushy fields 

 are familiar with the dense growth of bracken that is 

 now and then encountered, but one rarely thinks of it 

 as a noxious weed. In other parts of the world, how- 

 ever, it is less retiring. In British Columbia it is re- 

 ported as being often higher than a man's head, and in 

 the Southern Hemisphere a closely allied species or 

 variety, Pteris esculenta, not only covers considerable 

 areas with its tall fronds, but appears to be disposed to 

 spread into new territory. L. Cockayne writing of it in 

 The Plant World says : "No sooner is the forest de- 

 stroyed in some localities, the heath burned or the moor 

 drained ever so little, than, as if by magic, the bracken 



