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Elodea matthewsii

Interesting Facts

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Description

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Family Hydrocharitaceae

Herbs, annual or perennial , caulescent or without evident stem, glabrous or pubescent , entirely submersed , with both submersed and floating leaves, or with submersed stolons and emergent leaves, in fresh, brackish , or marine waters; turions rarely present. Stems rhizomatous , creeping , with abbreviated erect axis at nodes, or erect, leafy, elongate . Leaves basal, alternate, opposite, or whorled , sessile or petiolate ; stipules sometimes present, forming tubular sheath around stem; blade margins entire or serrate; veins 1--many. Inflorescences axillary , terminal , or scapose , 1-flowered or cymose , subtended by spathe ; spathe a 2-fid bract or pair of opposite bracts. Flowers unisexual , staminate and pistillate on same plants or on different plants, often with rudiments of opposite type, or bisexual , actinomorphic , rarely slightly zygomorphic; perianth epigynous , free , mostly 6-parted, then differentiated into sepals and petals, rarely 3-parted, then petals absent in Thalassia and Halophila; stamens (0--) 2--many in 1 or more whorls (inner often staminodial), epigynous, distinct or ± connate ; pollen spheric, in monads or tetrads or in slender chains; ovary 0--1, if present, inferior, 2--6[--16]-carpellate, 1-locular or falsely 6--9-locular; placentation parietal . Fruits berrylike. Seeds many, fusiform , ellipsoid , ovoid , or spheric; seed coat glabrous, papillose , or echinate .

Genera 17, species ca. 76 (10 genera, 14 species in the flora ) : nearly worldwide.

Hydrocharitaceae, like other members of the Alismatidae, have one or more (fewer than 20) scales (intravaginal squamules ) in the axils of their leaves. These scales (or hairs in some taxa) secrete mucilage and are without any venation . The structures are often referred to as "squamulae intravaginales" or "intravaginal scales" in the literature.[1]

Genus Elodea

Plants perennial , of fresh waters . Rhizomes and stolons absent. Erect stems rooted in substrate, branched or unbranched, elongate . Leaves cauline, whorled , 3--7 at each node, or leaves opposite at 4+ proximalmost nodes, submersed , sessile; blade linear to linear-lanceolate, apex acute; midvein without lacunae along side(s), blade uniform in color throughout;; abaxial surfacely without prickles or aerenchyma ; intravaginal squamules entire. Inflorescences solitary, sessile; spathes not winged . Flowers unisexual , staminate and pistillate on different plants, or rarely bisexual , usually projected to surface of water by elongate floral tube base , sessile; petals white. Staminate flowers : filaments distinct or 3 inner connate ½ their length ; anthers oval ; pollen in monads or tetrads . Pistillate flowers: ovary 1-locular; styles 3, not 2-fid. Fruits ovoid to lance-ellipsoid, smooth , dehiscing irregularly. Seeds cylindric to fusiform , glabrous to hirsute .

Species 5: North America, Central America, South America, Europe.[2]

Taxonomy

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Notes

Publishing author : H.St.John Publication : Darwiniana 12: 307 1961

Basionym author: (Planch.)

Similar Species

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Members of the genus Elodea

ZipcodeZoo has pages for 5 species, subspecies, varieties, forms, and cultivars in this genus:

E. bifoliata (Two Leaf Waterweed) · E. canadensis (American Waterweed) · E. nuttallii (Nuttall Waterweed) · E. schweinitzii (Schweinitz's Elodea) · E. verticillata (Florida Elodea)

More Info

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Further Reading

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Notes

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Contributors

Identifiers

Footnotes

  1. Robert R. Haynes "Hydrocharitaceae". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]
  2. "Elodea". in Flora of North America Vol. 22. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 7/22/2012