3.  CLIFF BRAKES. Pellaea

Sporangia borne on the upper part of the free veins inside the margins, in dot-like masses, but may run together, as in the continuous fruiting line of the bracken.  Indusium formed of the reflexed margins of the fertile segments which are more or less membranous. (Pellaea, from the Greek pellos, meaning dusky, in allusion to the dark stipes.)

(1) PURPLE CLIFF BRAKE. Pellaea atropurpurea

Stipes dark purple or reddish-brown, polished and decidedly hairy and harsh to the touch, at least on one side.  Fronds coriaceous, pale, simply pinnate, or bipinnate below; the divisions broadly linear or oblong, or the sterile sometimes oval, chiefly entire, somewhat heart-shaped, or else truncate at the stalked base.  Veins about twice forked.  Basal scales extending into long, slender tips, colorless or yellow.

[Illustration:  Purple Cliff Brake. Pellaea atropurpurea]

Another name is “the winter brake,” as its fronds remain green throughout the winter, especially in its more southern ranges.  It grows on rocky ledges with a preference for limestone, and often in full sun.  In large and mature fronds its pinnae are apt to be extremely irregular.  While its stipes are purplish, its leaves are bluish-green, and its scales light-brown or yellow.  Strange to say, this brake of the cliffs thrives in cultivation.  Woolson says of it, “This fern is interesting and valuable.  It is not only beautiful in design, but unique in color, a dark blue-green emphasizing all the varying tints about it—­a first-class fern for indoor winter cultivation.  It is a rapid grower, flourishing but a few feet from coal fire or radiator, in a north or south window.  It quickly forgives neglect, and if allowed to dry up out of doors or indoors, recovers in due time when put in a moist atmosphere.  It makes but one imperative demand, and that is the privilege of standing still.  Overzealous culturists usually like to turn things around, but revolving cliffs are not in the natural order of things.  The slender black stipes are very susceptible to changes of light and warped and twisted fronds result.”

Dry, calcareous rocks, southern New England and westward.  Rare.  Var. cristata has forked pinnae somewhat crowded toward the summit of the frond.  Missouri.

(2) SMOOTH CLIFF BRAKE

Pellaea glabella.  Pellaea atropurpurea, var. Bushii

Naked with a few, scattered, spreading hairs, smooth surface and dark polished stipes.  Rhizome short with membranous, orange or brown scales having a few bluntish teeth on each edge.  Pinnae sub-opposite, divergent, narrowly oblong, obtuse; base truncate, cordate or clasping, occasionally auricled; lower pinnae often with orbicular or cordate pinnules.  Sterile pinnae broader, bluish or greenish glaucous above, often crowded to overlapping.  The smooth cliff brake has a decidedly northern range, growing from northern Vermont to Missouri, and northwestward, but found rarely, if at all, in southern New England.