Isoëtes engelmannii

A. Braun

Flora 29: 178. 1846.

Common names: Engelmann's quillwort
Synonyms: Isoëtes valida (Engelmann) Clute
Treatment appears in FNA Volume 2.

Plants aquatic, emergent. Rootstock nearly globose, 2-lobed. Leaves evergreen, bright green, pale toward base, spirally arranged, to 60 (–90) cm, pliant, gradually tapering to tip. Velum covering less than 1/4 of sporangium. Sporangium wall usually unpigmented, occasionally ± brown-streaked. Megaspores white, 400–560 μm diam., reticulate, with unbroken lamellate ridges; girdle obscure. Microspores gray in mass, 20–30 μm, smooth to papillose. 2n = 22.


Phenology: Spores mature in summer.
Habitat: Emergent or in shallow water of lakes, ponds, streams, and ditches

Distribution

V2 513-distribution-map.gif

Ont., Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Ky., Md., Mass., Mich., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va.

Discussion

Isoëtes engelmannii is the most widely distributed quillwort of eastern North America. Plants with larger megaspores, ranging from 480–560 μm, have been called I. engelmannii var. georgiana Engelmann. This variety may represent a tetraploid cytotype. A tetraploid population of I. engelmannii (2n = 44) from northern Florida has larger megaspores characteristic of var. georgiana.

Isoëtes engelmannii hybridizes with I. echinospora [ = I. x eatonii Dodge (later synonym = I. x gravesii A. A. Eaton); I. flaccida; I. tuckermanii [ = I. x foveolata A. A. Eaton ex Dodge]; I. lacustris; and I. riparia [ = I. x brittonii Brunton & W. C. Taylor].

Selected References

None.

Lower Taxa

None.
... more about "Isoëtes engelmannii"
several +  and 1 +
W. Carl Taylor +, Neil T. Luebke +, Donald M. Britton +, R. James Hickey +  and Daniel F. Brunton +
A. Braun +
Engelmann's quillwort +
alternating +
Ont. +, Ala. +, Ark. +, Conn. +, Del. +, Fla. +, Ga. +, Ill. +, Ind. +, Ky. +, Md. +, Mass. +, Mich. +, Mo. +, N.H. +, N.J. +, N.Y. +, N.C. +, Ohio +, Pa. +, R.I. +, S.C. +, Tenn. +, Vt. +, Va. +  and W.Va. +
Emergent or in shallow water of lakes, ponds, streams, and ditches +
60 cm600 mm <br />0.6 m <br /> (90 cm900 mm <br />0.9 m <br />) +
pale +  and bright green +
straight +
evergreen +
recurved;erect;spreading +
tapering +
0 cm0 mm <br />0 m <br /> (60 cm600 mm <br />0.6 m <br />) +
deltate;cordiform +
0.1 cm1 mm <br />0.001 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
membranous +
smooth +  and papillose +
Spores mature in summer. +
lamellate +
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 />) +
brown-streaked +  and unpigmented +
Isoëtes valida +
Isoëtes engelmannii +
Isoëtes +
species +
brown-streaked;completely brown +
ephemeral +, evergreen +  and perennial +