2. Acrostichum Linnaeus, Sp. Pl. 2: 1067. 1753; Gen. Pl. ed. 5, 484, 1754.
Leather fern [Greek acros, at the end, tip, and stichos, row, referring to the distal spore-bearing pinnae]
Robert M. Lloyd
Plants terrestrial in fresh- or saltwater habitats. Stems erect or creeping, branched; scales dark brown, concolored, linear-lanceolate, margins entire. Leaves slightly dimorphic, clustered, 1--5 m. Petiole brown, with a single groove adaxially, glabrous, smooth or with scale scars, with several abaxial vascular bundles and 2 adaxial vascular bundles. Blade lanceolate, pinnate, leathery, abaxially glabrous or hispid, adaxially dull, not striate, glabrous; rachis straight. Pinnae stalked, free from rachis, narrowly oblong to lanceolate, 2--5 cm wide; base cuneate; stalk green; margins plane; fertile leaves bearing sporangia on most pinnae or on only more distal pinnae (fertile pinnae may be slightly smaller than sterile ones). Veins of pinnae conspicuous, strongly anastomosing. False indusia absent. Sporangia spread over abaxial surface, mixed with paraphyses (sori acrostichoid), containing 64 spores. Spores yellow, tetrahedral, minutely tuberculate or roughened, equatorial flange absent. x = 30.
Species 3, possibly more (2 in the flora): worldwide, warm and tropical regions.
SELECTED REFERENCES
Adams, D. C. and P. B. Tomlinson. 1979. Acrostichum in Florida. Amer. Fern J. 69: 42--46. García de López, I. 1978. Revisión del género Acrostichum en la República Dominicana. Moscosoa 1: 64--70. Lloyd, R. M. 1980. Reproductive biology and gametophyte morphology of New World populations of Acrostichum aureum. Amer. Fern J. 70: 99--110. Small, J. K. 1938. Ferns of the Southeastern States. Lancaster, Pa. [Facsimile edition 1964, New York and London.]
