Psilotum Swartz. Whiskfern.
A genus of 2 species, tropical and warm temperate. Psilotum lacks roots and true leaves. Other than the Australasian genus Tmesipteris, Psilotum has no close living relatives, and the 2 genera have sometimes been considered to comprise a distinct class (Wagner 1977), though PPG I (2016) treats the family in Order Psilotales in Subclass Ophioglossidae. The stem is chlorophyllous. Fungal cells interspersed in the outer layers of the rhizome aid in the absorption of nutrients.
ID notes: The stiff, dichotomously-branched habit of Psilotum is unmistakable.
Ref: Kramer & Green (1990); Lellinger (1985); PPG I (2016); Thieret (1993) In Flora of North America Editorial Committee (1993b); Wagner (1977); Zhang & Yatskievych in FoC (2013). Show full citations.
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