Isoëtes lacustris

Linnaeus

Sp. Pl. 2: 1100. 1753.

Common names: Lake quillwort isoète lacustre
Synonyms: Isoëtes hieroglyphica A. A. Eaton Isoëtes macrospora Durieu
Treatment appears in FNA Volume 2.

Plants aquatic, submerged. Rootstock nearly globose, 2-lobed. Leaves evergreen, dark green to reddish green, pala brown toward base, spirally arranged, to 25 cm, rigid, abruptly tapering to tip. Velum covering less than 1/2 of sporangium. Sporangium wall ± brown-streaked. Megaspores white, 55–750 μm diam., cristate to reticulate with branching to anastomosing ridges; girdle densely papillate or rarely smooth. Microspores gray in mass, 33–45 μm, paillose. 2n = 110.


Phenology: Spores mature late summer.
Habitat: Cool, oligotrophic, slightly acidic lakes and streams

Distribution

V2 398-distribution-map.gif

Greenland, Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Sask., Conn., Maine, Mass., Mich., Minn., N.H., N.Y., R.I., Tenn., Vt., Va., Wis., n, c Europe

Discussion

Population of Isoëtes lacustris in Tennessee and Virginia are disjunct.

North American plants of Isoëtes lacustris have been segregated as I. macrospora; both taxa are decaploids (2n = 110) and have similar leaf and spore morphology. Then cannot reliably be distinguished from each other except on the basis of geography.

Isoëtes lacustris is a totally submerged aquatic. Plants have been found at depths of more than 3 m. Plants with rugulate megaspores bearing smooth, rounded ridges and a smooth girdle have been called I. hieroglyphica A. A. Eaton [I. macrospora f. hieroglyphica (A. A. Eaton) N. E. Pfeiffer].

Isoëtes lacustris hibridizes with I. echinospora [ = I. x hickeyi W. C. Taylor & Luebke]; I. engelmannii; I. riparia [ = I. x jeffreyi D. M. Britton & Brunton]; and with I. tuckermanii [ = I. x harveyi A. A. Eaton].

Selected References

None.

Lower Taxa

None.
... more about "Isoëtes lacustris"
several +  and 1 +
W. Carl Taylor +, Neil T. Luebke +, Donald M. Britton +, R. James Hickey +  and Daniel F. Brunton +
Linnaeus +
Lake quillwort +  and isoète lacustre +
alternating +
Greenland +, Man. +, N.B. +, Nfld. and Labr. (Nfld.) +, N.S. +, Ont. +, P.E.I. +, Que. +, Sask. +, Conn. +, Maine +, Mass. +, Mich. +, Minn. +, N.H. +, N.Y. +, R.I. +, Tenn. +, Vt. +, Va. +, Wis. +, n +  and c Europe +
smooth +  and papillate +
Cool, oligotrophic, slightly acidic lakes and streams +
brown +, dark green +  and reddish green +
straight +
evergreen +
recurved;erect;spreading +
tapering +
0 cm0 mm <br />0 m <br /> (25 cm250 mm <br />0.25 m <br />) +
deltate;cordiform +
0.1 cm1 mm <br />0.001 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
membranous +
Spores mature late summer. +
branching +  and anastomosing +
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 hieroglyphica +  and Isoëtes macrospora +
Isoëtes lacustris +
Isoëtes +
species +
brown-streaked;completely brown +
ephemeral +, evergreen +  and perennial +