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Previous taxon Indexes to all accepted names and synonyms:
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W. Carl Taylor & Jon E. Keeley

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

I. nuttallii Engelm.
Plant terrestrial. Leaf: deciduous, generally > 8 cm, > 1 mm wide at middle, rigid, ± brittle, tapered to tip, light green to gray-green; base white to ± brown, 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, ± shiny, ± tubercled.
2n=22. Seasonally wet soil, temporary streams; generally < 1500(2760) m. North Coast Ranges, Cascade Range, Sierra Nevada, Sacramento Valley, n San Joaquin Valley, Central Western California (except Inner South Coast Ranges), South Coast, Peninsular Ranges, w Modoc Plateau; to British Columbia. Spores mature late spring, summer. [Online Interchange]
Unabridged note: Expanded author citation: Isoetes nuttallii A. Braun ex Engelm.

Previous taxon: Isoetes howellii
Next taxon: Isoetes occidentalis


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Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora,, accessed on Dec 1 2015
Citation for this treatment: [Author of taxon treatment] 2013. Isoetes, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on Dec 1 2015

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click for enlargement Isoetes nuttallii
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© 2003 Doreen L. Smith

Geographic subdivisions indicated for the distribution of Isoetes nuttallii Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.