A Dictionary of Choice Ferns. 
191 
CY ATHK A— cofitinued. 
These are borne on robust stalks, at first of a peculiar 
prune-colour, but ultimately becoming jet-black and highly 
polished. Before they are fully unfolded, the young fronds 
are densely clothed with long, black, chaffy scales, which 
later on change to a bright, light brown colour. In the 
fully-developed fronds, the stalks and also the midribs are 
rough with hard, glandular tubercles of a glossy nature 
and resembling a resinous exudation. The leaflets, fully 
3ft. long, are divided into secondary ones Sin. to Gin. long, 
about lin. broad, cleft nearly to the midrib, or again pin- 
nate; these are again cut into leafits or segments of an 
oblong or a narrow-oblong shape, blunt, coarsely toothed in 
the barren fronds, lobed and pinnatifid in the fertile ones, 
with the margins turned back. The sori, abundantly pro- 
duced and orange-yellow in colour, are disposed one to each 
lobule of the pinnule or lobe, and are situated about mid- 
way between the mid vein land the margin ; they are covered 
by circular involucres of parchment-like texture, which soon 
break open lat the summit with an irregular, often two- 
lobed margin. The whole surface of the frond is of a 
pleasing, bright green colour. 
C. medullaris is of very rapid growth; when planted in 
a conservatory where plenty of room can be allowed for 
its perfect development, it makes a good-sized stem or 
trunk in a comparatively short time. It is by far the most 
imposing of all known Tree Ferns that will succeed under 
cool treatment. Fig. 84. 
C. princeps. 
This is synonymous with C. insignis, a Fern more ex- 
tensively known in gardens as Cihotium princeps. 
CYRTOMIUM. ^eeAspidium. 
CYSTOPTERIS. 
Bladder Fern is the popular name of this small 
genus, all the species of which have their fronds twice 
or thrice divided, of thin texture, and with veins free. 
The distinguishing characters of the genus, how- 
ever, reside in each sorus, of a roundish form, being 
placed on the back of the veins and nrovided with a 
nearly globular involucre of a membranous nature, 
which is inserted by its broad base under the sorus, 
and at first covers it like a hood. ISTotwithstanding 
its being small, this genus, which is composed of 
