1. Pellaea atropurpurea (L.) Link (purple cliff brake) Pl. 14d,e,f; Map 63

P. atropurpurea f. cristata (Trel.) Clute

Rhizome scales reddish brown, linear. Leaves clustered, 5–50 cm long. Petioles and rachises dark reddish brown to black, densely hairy with short, curly hairs on the upper surface. Leaf blades 1–3 times compound, deltoid in outline, somewhat dimorphic. Leaflets 7–40 mm long, leathery, sometimes with 1–2 lobes at the base, the fertile leaflets narrowly triangular to linear, the sterile leaflets lanceolate to ovate or oblong, glabrous or sometimes with sparse, jointed hairs along the undersurface midvein. Sori in a continuous, marginal band around the pinnules, the edge of the recurved pinnule margins somewhat differentiated. Sporangia with 32 spores. Spores tan. 2n= 87 (apogamous). June–September.

Scattered nearly throughout the state, but most common in the Ozark Division (eastern and southwestern U.S.; southeastern Canada, Mexico, Guatemala). Crevices and ledges of limestone and dolomite bluffs, boulders, rock outcrops, and sinkholes, sometimes in soil of dry, rocky forests adjacent to dolomite glades.

The f. cristata refers to anomalous plants with pinnules forking at the tips. A rare hybrid between P. atropurpurea and P. glabella var. missouriensis has been recorded from Pulaski County. It was called Pellaea gastonyi Windham (1993b) in the Flora of North America, but that name is technically associated with plants of the western United States of somewhat different parentage. The apogamous tetraploid in Missouri is fertile and forms a local population on dolomite bluffs along the Gasconade River. Morphologically, the plants closely resemble the P. atropurpurea parent, but the petioles and rachises have only scattered, rather than dense, pubescence. This hybrid is to be expected at other sites where P. glabella var. missouriensis occurs.