Dennstaedtia is a mostly tropical and subtropical group of ferns described as a genus in 1801. Hayscented fern, or cup ferns, are common names for some species in this genus. It includes 58 species native to the tropical Americas, Madagascar, southern and eastern Asia, Australia, New Guinea, and the Pacific Islands.

Some characteristics of Dennstaedtia: "Fronds homomorphic; stipe grooved above, hairy when young... lamina triangular to oblong, many times pinnate, usually densely hairy, especially on rachis... Veins free, pinnately branching, veinlet not reaching margin, with hydathode at apex. Sori orbicular, marginal, terminal on each veinlet, separate..."

The temperate North-American hay-scented fern, Sitobolium punctilobulum, was formerly classified in Dennstaedtia and may have been its best-known member. It forms extensive clonal ground-cover colonies on level surfaces in the Appalachian area.

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