Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
For up-to-date information about California vascular plants, visit the Jepson eFlora.



W. Carl Taylor and Jon E. Keeley

Perennial, aquatic to terrestrial
Stem buried, corm-like, 2–3-lobed, corky, brown
Leaves simple, in grass-like tufts, spirally arranged on stem top, erect to spreading, < 25 cm, linear above base
Sporangia solitary, embedded in wide leaf base, < 1 cm, ± covered by a translucent membrane, either male or female; male spores > 10,000, < 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
Genera in family: 1 genus, 150 species: worldwide
Reference: [Pfeiffer 1922 Ann Missouri Bot Gard 9:79–233]



Etymology: (Greek: evergreen, from the habit of some species)
Perhaps most poorly known pteridophyte genus. Mature female spores, found in decaying leaf bases or soil, critical for identification; hand lens for texture when dry, microscope with micrometer for size. Hybrids (spores flattened, highly variable) common between aquatic species, making them less distinct.


I. nuttallii Engelm.

Plant terrestrial
Leaves deciduous, generally > 8 cm, > 1 mm wide at middle, rigid, almost brittle, gradually tapered to tip, light green to gray-green; bases white to brownish, outermost sterile, often surrounded by several black scales
Sporangium: membrane covering > 75%; male spores 0.02–0.03 mm, brown in mass; female spores 0.35–0.6 mm diam, ± shiny, ± tubercled
Chromosomes: 2n=22
Ecology: Seasonally wet soil, temporary streams
Elevation: generally < 1500 m.
Bioregional distribution: North Coast Ranges, Cascade Range Foothills, Sierra Nevada, n San Joaquin Valley, San Francisco Bay Area, Outer South Coast Ranges, South Coast, Peninsular Ranges
Distribution outside California: to British Columbia
Spores mature late spring, summer.

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bioregional map for ISOETES%20nuttallii being generated
YOU CAN HELP US make sure that our distributional information is correct and current. If you know that a plant occurs in a wild, reproducing state in a Jepson bioregion NOT highlighted on the map, please contact us with that information. Please realize that we cannot incorporate range extensions without access to a voucher specimen, which should (ultimately) be deposited in an herbarium. You can send the pressed, dried collection (with complete locality information indicated) to us (e-mail us for details) or refer us to an accessioned herbarium specimen. Non-occurrence of a plant in an indicated area is difficult to document, but we will especially value your input on those types of possible errors (see automatic conversion of distribution data to maps).

Retrieve Jepson Interchange Index to Plant Names entry for Isoetes nuttallii
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