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.
Pinnæ hispidulous, with white jointed hairs beneath.
Rocky Mountain Woodsia.
Fronds bright green, pinnæ glabrous, oblong.
Oregon Woodsia.
Fronds dull green, lanceolate, glandular beneath.
Cathcart's Woodsia.
Stipes obscurely jointed near the base:
Fronds more or less chaffy, pinnæ oblong to ovate,
crowded. Rusty Woodsia.
Fronds linear, smooth, pinnæ deltoid or orbicular.
Smooth Woodsia.
Fronds lanceolate, a few white scales beneath; pinnæ
deltoid-ovate. Alpine Woodsia.