FERN FAMILY. 13 
2. Cystopteris fragilis (L.) Bernh. Brittle Fern. (Fig. 24.) 
Polypodium fragile 1. Sp. Pl. 1ogt. 1753. 
Cystopleris fragilis Bernh. Schrad. Neues 
Journ. Bot. ©: Part 2, 27. 1806 
Rootstock short. Stipes 4’-S’ long ; leaves 
thin, oblong-lanceolate, only slightly taper- 
ing below, 4’-10’ long, 2-3-pinnatifid or pin- 
nate; pinnae lanceolate-ovate, irregularly 
pinnatifid, with a broad central space and 
bluntly or sharply toothed segments decur- 
rent along the margined or winged rachis, 
without bulblets; indusia narrow or acute 
at the free end, early withering and exposing 
the sori which finally appear naked ; texture 
membranous. 
On rocks and in moist grassy woods, New- 
foundland to Alaska, south to Georgia and Ari- 
zona. Also in South and Central America, 
Europe, Asia and New Zealand ; almost cosmo- 
politan in distribution. Ascends to 5000 ft. in 
New Hampshire. May-July. 
3. Cystopteris montana (Lam.) Bernh. Mountain Cystopteris. (Fig. 25.) 
Cystopteris montana Bernh. Schrad. Neues 
Journ. Bot. 1: Part 2, 26. 1806, 
Rootstock slender, widely creeping. Stipes 
Ler Ore long, slender ; leaves deltoid-ovate, 3-4- 
- pinnate, about 6’ long and broad, the lowest 
pinnae deltoid-lanceolate and much larger 
than the upper, their inferior pinnules 
1/-114’ long ; segments deeply divided into 
oblong lobes, deeply toothed; sori numer- 
ous; indusia acute, soon withering, expos- 
ing the sori and causing them to appear 
naked at maturity. 
On rocks, Labrador and Quebec to British 
Columbia, south to the north shore of Lake Su- 
perior, and in the Rocky Mountains to Colorado. 
Also in northern Europe and Asia. Aug. 
5. DRYOPTERIS Adans. Fam. Pl. 2: 20. 1763. 
[Asprp1uM Sw. Schrad. Journ. Bot. 2:4. 1So00. ] 
Ferns with 1-3-pinnate or pinnatifid leaves and round sori usually borne on the backs of 
the veins, the fertile and sterile leaves similar in outline. Indusium flat or flattish, orbicular 
and peltate or cordate-reniform, superior, fixed by its sinus or depressed centre. Stipe con- 
_ tinuous, not jointed with the rootstock. Sporanges abundant, pedicelled, the vertical ring 
bursting transversely. Veins free in the northern species, uniting occasionally or even freely 
in some of the southern. [Greek, signifying Oak-fern, in allusion to the forest habitat of 
most species. ] 
About 350 species, of wide geographic distribution. Besides the following some to others 
occur in the southern and western parts of North America. The first three species are sometimes 
separated as a distinct genus. (Polystichum Roth, 1797.) ‘ 
