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Family: Selaginellaceae Willk.

Kingdom: Plantae Rank: Family Parent: Selaginellales Status: Valid

Common Names:

  • SPIKE-MOSS FAMILY - English, United States of America

Other

Notes: An ancient, cosmopolitan but primarily tropical and subtropical family currently treated as a single genus with > 700 (Valdespino 1993) to perhaps 750 (Weakley 2010) species. Based on molecular studies, some authors speculate the genus will eventually be subdivided into a number of segregates (e.g., Weakley 2010; see discussion under genus). The earliest fossil evidence for the family is from the Carboniferous 350–330 million years ago (Rowe 1988; Korall & Kenrick 2002). However, Wikström (2001) noted that fossils in the isoetalean group from the late Devonian suggest the minimum age for the split between the lineages leading to Isoëtaceae and Selaginellaceae is 377 mya. As noted earlier, along with other Lycopodiophyta, they are part of an ancient evolutionary lineage that has been separate from all other vascular plants for around 400 million years (Pryer et al. 2004a). According to Korall et al. (1999), “Greatest diversity occurs in lowland to midmontane primary tropical rain forest, but this cosmopolitan family is also widely distributed in subtropical, temperate, montane, and rarely subarctic regions.” Selaginellaceae are usually terrestrial or epiphytic, superficially moss-like vascular plants bearing spores differentiated into microspores and megaspores (plants heterosporous). The leaves (lycophylls) usually have a single vein and a ligule (= minute, tongue-like basal protuberance on a leaf; the function is uncertain; however, they only occur on heterosporous species—Isoëtes and Selaginella). Recent molecular evidence supports the monophyly of the Selaginellaceae (Korall et al. 1999) and the family is apparently only distantly related to the Lycopodiaceae and Isoëtaceae. (Order Selaginellales)