Flora of the Canadian Arctic Archipelago

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S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, L.J. Gillespie, A.K. Brysting, H. Solstad, and J.G. Harris

Hippuris L.

Hippuridaceae, Mare's tail family.

Published in Sp. Pl. 4. 1753.

Vegetative morphology. Plants (4–)10–50(–150) cm high; herbs; perennial herbs; not caespitose; sometimes vegetatively proliferating by fragmentation; without milky juice; not glandular viscid. Only fibrous roots present. Ground level or underground stems horizontal; rhizomatous; elongate, or compact. Aerial stems developed; erect. Leaves present; heterophyllous, or not heterophyllous; distributed along the stems; whorled; not distinctly distichous; dying annually and non-persistent. Petioles absent. Sheaths absent. Leaf blade bases truncate. Blades (2–)10–80 mm long (aerial leaves usually less than 15 mm long), 0.3–4 mm wide, divaricate, straight, linear or lanceolate or oblanceolate, flat, appearing single-veined or with inconspicuous veins. Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blade margins flat, blades not lobed. Blade margins entire, glabrous; apices acuminate.

Reproductive morphology. Plants monoecious (1), or bisexual. Flowering stems circular or oval in cross section. Flowering stems with leaves; rooting at the lower nodes (especially in soft mud). Flowers solitary. Pedicels absent. Involucral bracts absent. Flowers small; bilaterally symmetrical (zygomorphic); bisexual. Sepals absent (reduced to an inconspicuous 2–4 lobed or sub-entire rim around the top of the ovary). Petals absent. Stamens 1. Anthers purple (turning brown). Ovary inferior; carpels 1; monomerous. Styles present. Stigmas per ovary 1. Placentation apical. Ovules per ovary 1. Fruit sessile; dry; an achene; oblong; brown; 1.8–1.9–2 mm long; 0.8–0.975–1.2 mm wide; glabrous; surface appearing veinless; not distinctly flattened; indehiscent. Seeds 1.

Chromosome information. 2n = 32.

General notes. The two species H. vulgaris and H. tetraphylla L.f. are related but differ in several morphological features (e.g., H. vulgaris has a mean of eight acute leaves in each whorl, H. tetraphylla has a mean of four short, obtuse leaves in each whorl) and in ecology. Hippuris vulgaris occurs mainly in fresh water but also transgresses into brackish waters.Intermediates between these two species are known and have been named as H. xlanceolata Retz.


This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.

Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.

Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.

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