Isoëtes riparia

Engelmann ex A. Braun

Flora 29: 178. 1846.

Common names: Shore quillwort isoète riparien
Synonyms: Isoëtes canadensis (Engelmann) A. A. Eaton Isoëtes saccharata Engelmann
Treatment appears in FNA Volume 2.

Plants usually aquatic, occasionally emergent. Rootstock nearly globose, 2-lobed. Leaves evergreen, bright green, pale toward base, spirally arranged, often twisted, to 35(–50) cm, pliant, gradually tapering to tip. Velum covering less than 1/2 of sporangium. Sporangium wall brown-streaked to completely brown. Megaspores white, 450-650 μm diam., cristate with isolated and branching, lamellate ridges; girdle obscure. Microspores gray to light brown in mass, 30–40 μm, tuberculate. 2n = 44.

Phenology: Spores mature late summer.
Habitat: Margins of lakes, ponds, and streams, tidal shores and estuaries


V2 127-distribution-map.gif

Calcareous to slightly acidic substrates in fresh, usually oligotrophic, water, Ont., Que., Conn., Del., Fla., Maine, Md., Mass., N.H., N.J., N.Y., N.C., Pa., R.I., S.C., Vt., Va., W.Va.


Megaspore morphology, electrophoretic profiles of leaf enzymes, and chromosome number provide evidence that Isoëtes riparia is an allotetraploid, formed by chromosome doubling in I. x eatonii, the primary diploid hybrid between I. echinospora and I. engelmanii. The considerable variation in leaf and spore morphology possibly results from multiple allotetraploid origins.

Isoëtes riparia hybridizes with I. echinospora [ = I. x dodgei A. A. Eaton]; I. engelmannii [ = I. x brittonii Brunton & W. C. Taylor]; I. lacustris [ = I. x jeffreyi D. M. Britton & Brunton); and I. tuckermanii.

Selected References


Lower Taxa

... more about "Isoëtes riparia"
W. Carl Taylor +, Neil T. Luebke +, Donald M. Britton +, R. James Hickey +  and Daniel F. Brunton +
Engelmann ex A. Braun +
Shore quillwort +  and isoète riparien +
Calcareous to slightly acidic substrates in fresh +, usually oligotrophic +, water +, Ont. +, Que. +, Conn. +, Del. +, Fla. +, Maine +, Md. +, Mass. +, N.H. +, N.J. +, N.Y. +, N.C. +, Pa. +, R.I. +, S.C. +, Vt. +, Va. +  and W.Va. +
Margins of lakes, ponds, and streams, tidal shores and estuaries +
Spores mature late summer. +
Isoëtes canadensis +  and Isoëtes saccharata +
Isoëtes riparia +
Isoëtes +
species +