References: Lellinger (1985); Cranfill in FNA (1993b).
A family of about 16 genera and 370 species, of cosmopolitan distribution.
1. Leaf blades elongate in outline, at least 4H as long as broad, membranaceous; sori globular, separate......Dennstaedtia punctilobula 1. Leaf blades broadly triangular in outline, about as broad as long, subcoriaceous; sori linear, confluent......Pteridium
References: Nauman & Evans in FNA (1993b).
A genus of about 45 species, of tropical to temperate distribution.
Dennstaedtia punctilobula (Michaux) T. Moore, Hay-scented Fern, Pasture Fern, Boulder Fern. Mt, Pd, Cp (NC, SC, VA): rocky or dry woodlands and forests, rock outcrops, pastures, clearings, roadbanks; common (uncommon in Piedmont, rare in Coastal Plain). June-September. Ranging from Nova Scotia and QuJbec west to MI, south to NC, n. GA, n. AL, and AR, progressively more montane southwards. This common species can be distinguished from other woodland ferns with deciduous fronds of similar size and shape (such as Athyrium, Dryopteris, and Thelypteris) by the following characteristics: leaves yellow-green or pale-green in color, with whitish-gray glandular trichomes, petioles silvery-pilose, leaves borne scattered (as clonal patches), sori tiny (less than 0.5 mm in diameter). Dennstaedtia is a large, pantropical genus; only D. punctilobula is temperate in distribution. Anatomical evidence indicates that it is not closely related to tropical Dennstaedtia, and its separation from that genus may be warranted. [= RAB, C, F, FNA, G, K, S, W]
Other species in eastern North America: Dennstaedtia bipinnata (Cavanilles) Maxon of FL.
Pteridium Gleditsch ex Scopoli (Bracken)
References: Jacobs & Peck in FNA (1993b).
A genus of two species, cosmopolitan in distribution.
1. Terminal segments of well-developed pinnules 2-4H as long as broad, about 3-7 mm wide, the margins usually pubescent; lower surface of rachis and costae shaggy pubescent..... P. aquilinum var. latiusculum
1. Terminal segments of well-developed pinnules 6-15H as long as broad, about 2-5 mm wide, the margins usually glabrous or sparsely pilose; lower surface of rachis and costae glabrous or sparsely pilose...... P. aquilinum var. pseudocaudatum
Pteridium aquilinum (Linnaeus) Kuhn var. latiusculum (Desvaux) Underwood ex Heller, Eastern Bracken. Mt, Pd, Cp (NC, SC, VA): mainly in dry woodlands, forests, and heath balds, up to 1600m in elevation; common (rare in Coastal Plain). July-September. The species is nearly worldwide in distribution; var. latiusculum is itself widely distributed, occurring in most of North America (largely replaced by var. pseudocaudatum in the Southeast), in Mexico, and in Eurasia. [= RAB, C, F, FNA, G, K, W; P. latiusculum (Desvaux) Hieronymus var. latiusculum -- S]
Pteridium aquilinum (Linnaeus) Kuhn var. pseudocaudatum (Clute) Heller, Tailed Bracken, Southern Bracken. Cp, Pd (NC, SC, VA): mainly in dry sandy woodlands, often locally abundant in sandhills and flatwoods; common (uncommon in Piedmont). July-September. Var. pseudocaudatum is primarily a variety of the Southeastern Coastal Plain (where it is ubiquitous and abundant), but ranges north to MA, OH, IN, s. MI, and MO. [= RAB, C, F, FNA, G, K, W; P. latiusculum (Desvaux) Hieronymus var. pseudocaudatum (Clute) Maxon -- S]
Other species in eastern North America: Pteridium caudatum (Linnaeus) Maxon of FL.
Pteridium is a notorious and nearly worldwide weed (though less consequential in our area than in many parts of the world), nearly impossible to eradicate because of its deeply subterranean rhizomes. Bracken fiddleheads are sometimes eaten, but they are poisonous and highly carcinogenic. Bracken is not favored by grazing animals, and increases its abundance under grazing pressure. In overgrazed pastures, however, cattle will graze on bracken, the carcinogenic compound (shikimic acid) then transmittable to humans through milk.
Other genera and species in eastern North America: Hypolepis repens (Linnaeus) C. Presl of FL. Odontosoria clavata (Linnaeus) J. Smith of FL.
Flora of the Carolinas and Virginia, Working Draft of 27 October 1997 -- KEY TO PTERIDOPHYTE GENERA. Alan S. Weakley. The Nature Conservancy, Southeast Regional Office, Southern Conservation Science Department.