Jepson Flora Project: Jepson Interchange    

 
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ISOETACEAE

QUILLWORT FAMILY

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]

ISOETES

QUILLWORT


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.

Native

I. echinospora Durieu

Plant underwater
Leaves ± evergreen, < 20 cm, soft, flexible, gradually tapered to tip, bright green; bases white to brownish
Sporangium: membrane covering < 50%; male spores 0.02–0.03 mm, gray in mass; female spores 0.4–0.5 mm diam, prickly
Chromosomes: 2n=22
Ecology: Persistent lakes, pools
Elevation: > 1500 m.
Bioregional distribution: Klamath Ranges, n High Sierra Nevada
Distribution outside California: to Alaska, eastern N.America, Eurasia
Synonyms: I. braunii Durieu; I. muricata Durieu
Hybridizes with I. bolanderi , I. occidentalis. Spores mature late summer.

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