116 CYSTOPTERIS FRAGIT.ns, 
f CYSTOTTERIS FRA'GILIS 
THIS Fern has been also called by modern botanists 
Polypodium fragile, Polypodium album, Oyatheafragilis, 
and Aspidium fragile. Fragileness or brittleness is a 
striking characteristic of its stems, and as in its Latin 
names this is uniformly alluded to, so is it in its English 
title of Brittle Bladder Fern, and Brittle Polypody. 
Boot tufted, scaly, black, and having numerous fibrous 
rootlets ; it extends slowly, throwing out fresh crowns 
around the old one. Fronds many together, usually about 
six inches high, though in favourable situations, warm, 
moist, and shaded, they attain to nearly twelve inches. 
Their general outline is spear-headed but sharp-pointed, 
and their colour a bright green. The leaflets have the 
same spear-head form as the fronds, but are not so 
sharply pointed; they are not quite opposite, but so 
nearly so as scarcely to be described as alternate ; they 
clothe rather more than half the stem, and are not re- 
gularly arranged. The leafits are usually alternate, 
pointed-egg-shaped, but in barrep fronds blunt, tapering 
at the base and decurrent, their eSge deeply, numerously, 
and sharply toothed ; the lower leafits are so deeply cut 
sometimes as to be nearly formed into smaller leafits, 
and such form may be described as doubly-leafited. 
Stem reddish-brown, becoming almost black, very slender, 
brittle, juicy, smooth, but with a few scales at the very 
bottom. The fructification on almost all the side-veins, 
and near their end. It is in round masses, numerous, 
