








THE BRITISH FERNS. 
' or vesicles, which contain the spores. These vesicular bodies, 
known as the spore-cases, are placed on the surface or on the 
margin of the leaves, and consist of small hollow cells without 
internal divisions or partitions, containing each a great quantity of 
the spores, which latter are of microscopical proportions, and all 
possessing the same general structure. 
It wil thus have become evident that the Ferns are to be known 
from the great group of Flowering plants, by their not producing 
either flowers or seeds, properly so ealled; while they are known 
from other Flowerless plants by the combination of these charac- 
teristics :—(1), their spore-cases are borne on the back or at the 
edges of their leaves; (2), they are all one-celled; and, (3), the 
spores they contain are all of one kind. 
The Ferns are plants of very varied size and aspect. The 
majority of them are dwarf terrestrial herbs; many of them are 
epiphytal; some are, minute plants of delicate structure; while 
others, again, form noble trees with stems of fifty feet or upwards 
in height, crowned by magnificent plumy heads of fronds. Mr. 
Ralph states, that in the Cyathea medullaris,* one of the tree 
Ferns of New Zealand, he has counted three dozen of the fronds in 
full vigour in one of these crowns at one time, the fronds being 
twelve feet or upwards in length, and requiring considerable effort 
to raise them when cut off and lying on the ground. Nor is their 
form or. cutting less varied, all gradations of outline being met 
with from linear to lance-shaped or deltoid, and all intermediate 
states of division, between the simple or undivided frond, and that 
in which division and subdivision of the parts is so many times: 
repeated, as to produce a highly composite character. 
The elegant characters of outline and subdivision of parts so 
commonly found in the fronds of Ferns, have led to their being 
* Ralph, in Journal of Proceedings of Linnean Society, iii. 166. 

