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Key to families | Table of families and genera
Indexes to all accepted names and synonyms:
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Perennial herb, aquatic to terrestrial. Stem: buried, corm-like, 2–3-lobed, corky, brown. Leaf: simple, in grass-like tufts, spirally arranged on stem top, erect to spreading, < 30 cm, linear above base. Sporangium: solitary, embedded in wide leaf base, < 1 cm, ± covered by a translucent membrane, male or female; male spores > 10000, < 0.045 mm, ± bean-shaped, gray or brown in mass; female spores 20–200, 0.2–0.7 mm, spheric, white, ± smooth, ridged, tubercled, or prickly.
1 genus, 200+ species: worldwide. [Taylor et al. 1993 FNANM 2:64–75] —Scientific Editors: Alan R. Smith, Thomas J. Rosatti.
Unabridged references: [Pfeiffer 1922 Ann Missouri Bot Gard 9:79–233]
(Greek: evergreen, from habit of some species) Perhaps most poorly known lycophyte genus. Mature female spores, found in decaying leaf bases or soil, critical for identification, as are hand lens for texture when dry, microscope with micrometer for size. Hybrids (spores of variable size, shape) common between aquatic species, making them less distinct.Key to Isoetes
Plant becoming terrestrial. Leaf: deciduous, < 30 cm, rigid, not brittle, tapered to tip, bright green; base ± brown to black. Sporangium: membrane covering < 75%; male spores 0.025–0.035 mm, brown in mass; female spores 0.3–0.5 mm, ridged.
2n=22. Vernal pools, lake margins; generally < 1500 m. Klamath Ranges, North Coast Ranges, Cascade Range, Sierra Nevada Foothills, Great Central Valley, San Francisco Bay Area, South Coast Ranges, South Coast, Peninsular Ranges; to Washington, Montana, Utah. Small plants of South Coast, Washington, Baja California (leaf < 10 cm, female spore < 0.42 mm) are assignable to Isoetes howellii var. minima (A.A. Eaton) N. Pfeiff., recognition of which remains questionable pending further research, although it is ± clear that it should not be treated as an infraspecific taxon of Isoetes howellii. Spores mature late spring, summer. [Online Interchange]
Previous taxon: Isoetes echinospora
Next taxon: Isoetes nuttallii
Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on Mar 11 2014
Citation for this treatment: [Author of taxon treatment] 2012. Isoetes, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=29392, accessed on Mar 11 2014
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© 2007 Neal Kramer
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