4. LIP FERNS. _Cheilánthes_

Mostly small southern ferns growing on rocks, pubescent or tomentose with
much divided leaves. Sori at the end of the veins at first small and
roundish, but afterwards more or less confluent. The indusium whitish and
sometimes herbaceous, formed of the reflexed margin of the lobes or of the
whole pinnule. Veins free, but often obscure. Most of the ferns of this
genus grow in dry, exposed situations, where rain is sometimes absent for
weeks and months. For this reason they protect themselves by a covering
of hairs, scales or wool, which hinders the evaporation of water from the
plant by holding a layer of more or less saturated air near the surface of
the frond. (In Greek the word means _lip flower_, alluding to the lip-like
indusia.)

(1) ALABAMA LIP FERN. _Cheilánthes alabaménsis_

Fronds smooth, two to ten inches long, lanceolate, bipinnate. Pinnæ
numerous, oblong-lanceolate, the lower usually smaller than those above.
Pinnules triangular-oblong, mostly acute, often auricular or lobed at the
base. Indusia pale, membranous and continuous except between the lobes.
Stipes black, slender and tomentose at the base.

[Illustration: Alabama Lip Fern. _Cheilanthes alabamensis_ (From Waters's
"Ferns," Henry Holt & Co.)]

This species of lip fern may be distinguished from all the others within
our limits by its smooth pinnæ. On rocks--mountains of Virginia to