4. Histiopteris (J. Agardh) J. Smith, Hist. Fil. 294. 1875.
栗蕨属 li jue shu
Authors: Wenbo Liao, Ding Mingyan, Zhaohong Wu & Jefferson Prado
Pteris sect. Histiopteris J. Agardh, Recens. Spec. Pter. 76. 1839.
Plants terrestrial, climbing. Rhizome thick and long creeping, vascular system a corrugate solenostele, densely clothed with lanceolate, thick, castaneous-brown scales. Fronds sparse, large, indeterminate; stipe reddish castaneous, shiny, long, terete, glabrous; costae same as stipes in color, slightly grooved adaxially; lamina 2- or 3-pinnate, triangular, papery to subleathery, glabrous, basally usually pallid; pinnae opposite, often sessile; pinnules at base a pair, auricle-like; pinnules opposite; venation reticulate, without included veinlets. Sori along margin of lamina, with collecting vein near margin, protected by a narrowly linear false indusium formed by a membranous margin, paraphyses present, without velum; indusia long stalked and annulus composed of 18 thick-walled cells; spores dihedral, oblong to reniform, hyaline, with prominent wart. x = 12.
About seven species: widely distributed in pantropical regions, southward to the Cape of Good Hope of Africa, Australia (Tasmania), and islands near Antarctica; sometimes those species treated as one species; one species in China.
Histiopteris is morphologically similar to Pteris but molecular data indicates that this similarity is superficial and that Histiopteris belongs to the Dennstaedtiaceae. It differs from Pteris by the long-creeping rhizome, with bristlelike, chestnut-brown scales; proliferous apex of the lamina; opposite pinnae and pinnules, and pinna bases with a pair of reduced, auricle-like pinnules; all veins anastomosing, and forming a row of narrow areoles on both sides of the costules; and dihedral, hyaline spores.