4. Pityrogramma Link, Handbuch. 3: 19. 1833.
Silverback fern, goldback fern [Greek pityros, bran, and gramma, lines (as in written characters), referring to the farina covering the abaxial leaf blade surface]
Michael D. Windham
Plants terrestrial [or on rock]. Stems erect or nearly so, unbranched; scales brown, concolored or nearly so, lanceolate, margins entire. Leaves monomorphic, closely spaced, 25--150 cm. Petiole black to purplish black or reddish brown, longitudinally grooved adaxially, glabrous, with 2(--3) vascular bundles. Blade linear-lanceolate to ovate or elongate-triangular, 1--4-pinnate, herbaceous to leathery, abaxially usually farinose, farina white or yellow, sometimes partially or completely replaced by trichomes, adaxially glabrous, dull, not striate; rachis straight. Ultimate segments stalked or sessile, free from costa or partially adnate to it, narrowly triangular to linear, entire or lobed; base narrowly cuneate, stalks when present green, not lustrous; margins not recurved to form false indusia. Veins of ultimate segments free, obscure, pinnately branched and divergent distally. False indusia absent. Sporangia scattered along veins, containing 32 or 64 spores, intermixed with farina-producing glands. Spores tan with dark brown ridges, tetrahedral-globose, perispore usually reticulate, with equatorial flange (except in Pityrogramma trifoliata ). Gametophytes glabrous.
Species ca. 15 (2 in the flora): primarily neotropical, some in Africa, introduced elsewhere in Eastern Hemisphere.
The name Nesoris bicolor Rafinesque was based on a yellow-farinose plant from Florida and presumably represents a species of Pityrogramma . A type has not been located, and C. S. Rafinesque's (1836[--1838]b, part 4) description is not precise enough to permit equation of this name with modern nomenclature. No yellow-farinose Pityrogramma has since been reported from Florida.
Pentagramma has been segregated from Pityrogramma (G. Yatskievych et al. 1990) and comprises what was the Pityrogramma triangularis (Kaulfuss) Maxon complex.
Tryon, R. M. 1962. Taxonomic fern notes. II. Pityrogramma (including Trismeria) and Anogramma. Contr. Gray Herb. 189: 52--76.
(Key to species of Pityrogramma)