Ophioglossaceae | |
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Ophioglossum vulgatum | |
Scientific classification | |
Kingdom: | Plantae |
Division: | Pteridophyta |
Class: | Psilotopsida |
Order: | Ophioglossales |
Family: | Ophioglossaceae |
Genera | |
Ophioglossaceae, the Adder's tongue family, is a family of ferns, currently thought to be most closely related to Psilotaceae, the two together comprising the class Psilotopsida as the sibling group to the rest of the ferns. The Ophioglossaceae is one of two groups of ferns traditionally known as eusporangiate fern. The number of genera included in the family varies between different authors' treatments, and most conservatively the family is treated as containing four genera, Ophioglossum, Botrychium, Helminthostachys, and Mankyua (placed in two to four separate families in other treatments). A broad definition of the family and its genera have been taken in several recent treatments (e.g., Wagner 1990, Smith et al. 2006, and in the Flora of North America). A notable exception is the classification of Kato (1987), who advocated the division of Botrychium into four genera: Botrychium s.s., Sceptridium, Japanobotrychium, and Botrypus.
These ferns differ from the other ferns in several respects:
Members of Ophioglossaceae are usually terrestrial (excepting a few epiphytic species of Ophioglossum) and occur in both temperate and tropical areas. The leaves are usually fleshy, and in temperate areas will often turn brownish or reddish during colder months. In addition to having mycoheterotrophic gametophytes, there are a few members of Botrychium that are unique among ferns in having the sporophytes also mycoheterotrophic, producing only small, ephemeral sporophylls that do not photosynthesize.