Dennstaedtiaceae

Plants perennial, mostly terrestrial, rarely epiphytic, generally in mesic, forested habitats. Stems short- to long-creeping, solenostelic [protostelic], bearing hairs (or less often scales), often branching by means of buds on proximal part of petiole. Leaves monomorphic, circinate in bud. Petiole not articulate, with 1–many vascular bundles, hairy or glabrous [scaly]. Blade 1-pinnate to decompound (rarely simple), glabrous or hairy or with mixture of hairs and glands; rachis and costae grooved adaxially [not grooved in some genera]. Veins free or sometimes joined at margin in fertile segments, pinnate or forking in ultimate segments. Sori near or at blade margin on vein tips or submarginal commissural vein; true (inner) indusia present, free or fused with portion of blade margin to form cup or pouch, or obscured by revolute and usually modified portion of blade margin [indusia rarely absent]; sporangial stalk of 1–3 rows of cells. Spores not green, tetrahedral or bilateral, monolete or trilete. Gametophytes green, cordate, with archegonia and antheridia borne on lower surface.

Distribution

Worldwide, mostly tropical.

Discussion

The family is variously circumscribed, in the strict sense including only eight genera, while in the broadest sense encompassing about half the recognized genera of higher ferns (R. E. Holttum 1947). Here it is delimited in the sense of J. T. Mickel (1973). Characteristics that define the family include submarginal or marginal sori with generally two indusia, an inner true indusium and an outer false indusium formed by the revolute, often modified segment margin (although either type may be reduced or absent in some genera); indument usually of hairs rather than scales; and long-creeping protostelic or solenostelic stems with stem buds on the bases of the petioles. Not all genera in the family share all the characteristics.

Genera ca. 20, species perhaps 400 (4 genera, 6 species in the flora).

Selected References

Holttum, R. E. 1947. A revised classification of the leptosporangiate ferns. J. Linn. Soc., Bot. 51: 123--158.

Mickel, J. T. 1973. Position of and classification within the Dennstaedtiaceae. In: A. C. Jermy et al., eds. 1973. The Phylogeny and Classification of the Ferns. London. Pp. 135--144. [Bot. J. Linn. Soc., Suppl. 1.]

Lower Taxa

Dennstaedtia, Hypolepis, Odontosoria, Pteridium

Illustrations

	Family ⠉	Taxon	Illustrator ⠉
	Dennstaedtiaceae Dennstaedtiaceae Dennstaedtiaceae	Hypolepis repens Odontosoria clavata Dennstaedtia punctilobula	John Myers John Myers John Myers
	Dennstaedtiaceae Dennstaedtiaceae Dennstaedtiaceae	Pteridium aquilinum var. latiusculum Pteridium aquilinum var. pseudocaudatum Pteridium aquilinum var. caudatum	John Myers John Myers John Myers

Key

1	Sori continuous along margins of segments; inner indusium, if present, hidden by reflexed margin of blade and maturing sporangia; blades usually broadly triangular.	Pteridium
1	Sori distinct, not continuous along margins of ultimate segments; inner indusium present or absent; blades narrowly deltate to lanceolate to ovate.	> 2
2	Sori at tips of ultimate segments; veins dichotomously forked.	Odontosoria
2	Sori lateral on ultimate segments; veins pinnately branched.	> 3
3	Inner indusium absent, outer indusium recurved over sori.	Hypolepis
3	Inner indusium present, outer indusium fused with inner one to form cup or tubular structure containing sporangia.	Dennstaedtia