Pteridium Gled. ex Scop.
-
Authority
Proctor, George R. 1989. Ferns of Puerto Rico and the Virgin Islands. Mem. New York Bot. Gard. 53: 1-389.
-
Family
Dennstaedtiaceae
-
Scientific Name
-
Description
Species Description - Weedy tenestrial fems. Rhizomes deeply subtenanean, black, extensively creeping, repeatedly branched, clothed toward apex with reddish-brown, pluricellular, articulate hairs. Fronds of medium to rather large size, usually of coarse, hard texture, mostly 3- to 4-pinnate and of broadly deltate or oblong-deltate outline, the lower pinnae with glandular "nectaries" at base when young, these exuding a substance attractive to ants; ultimate segments variable in size and shape but always with revolute margins; veins all free. Sori marginal and usually continuous, the sporangia b o m e between an outer "false" indusium (the reflexed modified margin ofthe segment) and an inner one of variable stmcture, on a vascular strand connecting the vein-tips; paraphyses absent. Sporangia with annulus of ca. 13 cells; spores tetrahedral-globose, the surface inegularly granulate or with particles more or less fused to form minute projections.
-
Discussion
Type Species. Pteridium aquilinum (Linnaeus) Kuhn, based on Pteris aquilina Linnaeus, a highly variable species of worldwide distribution. The genus is considered monotypic, with 12 geographic varieties. The generic name is derived from the Greek pteridion, a small fem.
Special Literature. Tryon, R. M . 1941. Revision of the genus Pteridium. Contr. Gray Herb. 134: 1-70. (reprinted from Rhodora 43: 1-31, 37-67, /. 650-653. 1941); Tryon, R. M . & A. F. Tryon. 1982. Fems and allied plants, pp. 387-394, 12 figs.; Power, M . S. & J. E. Skog. Ultrastructure of the extrafloral nectaries of Pteridium aquilinum. Amer. F e m J. 77: 1-15, 13 figs.