Isoëtes occidentalis

L. F. Henderson

Bull. Torrey Bot. Club 27: 358. 1900.

Common names: Western quillwort
Synonyms: Isoëtes flettii (A. A. Eaton) N. E. Pfeiffer Isoëtes lacustris var. paupercula Engelmann Isoëtes paupercula (Engelmann) A. A. Eaton Isoëtes piperi A. A. Eaton
Treatment appears in FNA Volume 2.

Plants aquatic. Rootstock nearly globose, 2-lobed. Leaves evergreen, dark green, pale toward base, spirally arranged, to 20 cm, rigid, gradually tapering to tip. Velum covering less than 1/2 sporangium. Sporangium wall unpigmented. Megaspores 500–700 μm diam., cristate, tuberculate, rugulate, or echinate with ridges, tubercles, or spines; girdle smooth. Microspores brown in mass, 35–45 μm, papillose to spinulose. 2n = 66.


Phenology: Spores mature in late summer.
Habitat: Lakes

Distribution

V2 479-distribution-map.gif

B.C., Alaska, Calif., Colo., Idaho, Mont., Oreg., Utah, Wash., Wyo.

Discussion

Megaspores of Isoëtes occidentalis are variable in wall pattern. Populations exist with rugulate or tuberculate megaspores and other population with cristate to echinate megaspores. Plants with thin-walled megaspores that crack easily have been called I. paupercula. Populations in which megaspores have short ridges and tubercles in a band along the equator have been called I. flettii. Populations with broad-based tubercles on the megaspores have been called I. piperi. The variation in megaspore pattern may indicate multiple allopolyploid origins for I. occidentalis.

The general aspect of Isoëtes occidentalis and its tough, dark green leaves suggested to early workers an affinity with I. lacustris.

Isoëtes occidentalis hybridizes with I. bolanderi, I. echinospora, and I. maritima [ = I. x truncata (A. A. Eaton) Clute].

Selected References

None.

Lower Taxa

None.
... more about "Isoëtes occidentalis"
several +  and 1 +
W. Carl Taylor +, Neil T. Luebke +, Donald M. Britton +, R. James Hickey +  and Daniel F. Brunton +
L. F. Henderson +
Western quillwort +
alternating +
B.C. +, Alaska +, Calif. +, Colo. +, Idaho +, Mont. +, Oreg. +, Utah +, Wash. +  and Wyo. +
Lakes +
pale +  and dark green +
straight +
evergreen +
recurved;erect;spreading +
tapering +
0 cm0 mm <br />0 m <br /> (20 cm200 mm <br />0.2 m <br />) +
deltate;cordiform +
0.1 cm1 mm <br />0.001 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
membranous +
black +, gray +  and white +
rugulate +  and tuberculate +
Spores mature in late summer. +
Bull. Torrey Bot. Club +
branched +  and simple +
2-lobed +  and globose +
0.3 cm3 mm <br />0.003 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Isoëtes flettii +, Isoëtes lacustris var. paupercula +, Isoëtes paupercula +  and Isoëtes piperi +
Isoëtes occidentalis +
Isoëtes +
species +
brown-streaked;completely brown +
ephemeral +, evergreen +  and perennial +