oblong-lanceolate, five to twelve
inches long, twice pinnate, the pinnae often pinnatifid or cut-toothed,
ovate-lanceolate, decurrent on the winged rachis. Indusium appearing acute
at the free end. Very variable in the cutting of the pinnules.

The fragile bladder fern, as it is often called, and which the name
_fragilis_ suggests, is the earliest to appear in the spring, and the
first to disappear, as by the end of July it has discharged its spores and
withered away. Often, however, a new crop springs up by the last of August,
as if Nature were renewing her youth. In outline the fragile bladder fern
suggests the blunt-lobed Woodsia, but in the latter the pinnae and pinnules
are usually broader and blunter, and its indusium splits into jagged lobes.
Rather common in damp, shady places where rocks abound. In one form or
another, found nearly throughout the world though only on mountains in the
tropics.

[Illustration: Fragile Bladder Fern, Fruited Portion]

[Illustration: Fragile Bladder Fern. _Cystopteris fragilis_ (Wakefield,
Mass.)]

KEY TO THE WOODSIAS

Stipes not jointed:
Indusium ample, segments broad, frond without hairs.
Obtuse Woodsia.
Pinnae hispidulous, with white jointed hairs beneath.
Rocky Mountain Woodsia.
Fronds bright green, pinnae glabrous, oblong.
Oregon Woodsia.
Fronds dull green, lanceolate, glandular beneath.
Cathcart's Woodsia.
Stipes obscurely jointed near the base:
Fronds more or less chaffy, pinnae oblong to ovate,
crowded. Rusty Woodsia.
Fronds linear, smooth, pinnae deltoid or orbicular.
Smooth Woodsia.
Fronds lanceolate, a few white scales beneath; pinnae
deltoid-ovate. Alpine Woodsia.

THE WOODSIAS

Small, tufted, pinnately divided ferns. Fruit-dots borne on the back of
simply forked, free veins. Indusium fixed beneath the sori, thin and often
evanescent, either small and open, or early bursting at the top into
irregular pieces or lobes. (Named for James Woods, an English botanist.)

(1) RUSTY WOODSIA. _Woodsia ilvensis_

Fronds oblong-lanceolate, three to ten inches high, rather smooth above,
thickly clothed underneath with rusty, bristle-like chaff. Pinnate, the
pinnae crowded, ses