Dennstaedtia Bernh., J. Bot. (Schrader) 1800

Schwartsburd, Pedro B., Navarrete, Hugo, Smith, Alan R. & Kessler, Michael, 2017, Prodromus of a fern flora for Bolivia. XXVI. Dennstaedtiaceae, Phytotaxa 332 (3), pp. 251-268 : 252-253

Dennstaedtia Bernh., J. Bot. (Schrader) 1800 (2): 124. 1800 [1801].

Dennstaedtia has short-to long-creeping or ascending, dorsiventral, glabrous to densely pubescent or setose rhizomes, unbranched, or in few species dichotomously branched. These provide important information for identification and should be collected or at least described. In some treatments, the species of Dennstaedtia are said to always have pubescent rhizomes, but some species are glabrous or glabrescent. Different types of rhizomes may have different types of roots: some species with long-creeping, slender rhizomes are pubescent with stout roots, while others are glabrous with fibrous roots. The petioles are glabrous to pubescent, with or without roots at the bases, and petiolar buds are present in most species; these may initiate new secondary rhizomes. Leaves are erect, arching or scandent, up to 4-pinnate-pinnatifid, and up to 7 m long, thereby among the longest leaves of Bolivian ferns. Mature leaves sometimes bear laminar or axillary bulbils (sometimes called buds)—diminutive plants bearing leaves or leaf primordia, rhizome, and roots-which may develop in situ when the leaf falls to the ground; this may result in vegetative reproduction. In Dennstaedtia sprucei , detachable spherical, pubescent bulbils are borne on the veins or axis of the blades. The sori are marginal, and the indusia cup-or purse-shaped. The large leaves and marginal sori render the genus easy to recognize. Dennstaedtia is a pantropical genus, with 50–70 species ( Tryon 1960, Navarrete & Øllgaard 2000, PPG I 2016).

Studies suggest that Dennstaedtia is probably not monophyletic; rather it may be an artificial assemblage ( Kramer 1990). However, it is likely that the neotropical species form a monophyletic clade ( Perrie et al. 2015). Application of some names must await further sampling, because types and/or representative specimens of various competing names have not yet been sampled in any molecular analysis. Most species grow within forests, adjacent to ravines; however,

D. cicutaria occupies disturbed areas, and its life form and rhizomes are quite similar to many species of Hypolepis . Dennstaedtia glauca may occur in open areas.