An Illustrated Flora of the Northern United States, Canada and the British Possessions/Vallisneriaceae
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Family 8.
Vallisneriàceae
Dumort.
Anal. Fam. 54.
1829.
Tape-grass Family.
Submerged or floating aquatic herbs, the leaves various. Flowers regular, mostly dioecious, appearing from an involucre or spathe of 1-3 bracts or leaves. Perianth 3-6-parted, the segments either all petaloid or the 3 outer ones small and herbaceous, the tube adherent to the ovary at its base in the pistillate flowers. Stamens 3-12. Anthers 2-celled. Ovary 1-celled with 3 parietal placentae. Styles 3, with entire or 2-cleft stigmas. Ovules anatropous or orthotropous. Fruit ripening under water, indehiscent. Seeds numerous, without endosperm.
About 6 genera and 25 species of wide distribution in warm and temperate regions. Besides the following, another genus, Halophila, occurs on the coast of Florida.
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| • | Stem branched ; leaves whorled or opposite. | 1. | Philotria. | |||||||||
| • | Acaulescent ; stoloniferous ; leaves grass-like, elongated. | 2. | Vallisneria. | |||||||||
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1.0 edit
1.
Philòtria
Raf.
Am. Month. Mag. 2: 175.
1818.
[Elodea Michx. Fl. Bor. Am. 1: 20. 1803. Not Elodes Adans. 1763.]
Stems submerged, elongated, branching, leafy. Leaves opposite or whorled, crowded, 1-nerved, pellucid, minutely serrulate or entire. Flowers dioecious or polygamous, arising from an ovoid or tubular 2-cleft spathe. Perianth 6-parted, at least the 3 inner segments petaloid. Staminate flowers with 9 stamens, the anthers oblong, erect. Ovary 1-celled with 3 parietal placentae. Stigmas 3, nearly sessile, 2-lobed. Fruit oblong, coriaceous, few-seeded. [Name from the Greek, referring to the leaves, which are often whorled in three's.]
About 10 American species. Type species Elodea canadensis Michx.
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| • | Leaves oblong or ovate-oblong, mostly obtuse; staminate flowers unknown. | 1. | P. canadensis. | |||||||||
| • | Leaves linear or oblong, acute; hermaphrodite flowers unknown. | |||||||||||
| • | Leaves oblong or linear-oblong, 1″–1½″ wide wide; spathe of the staminate flowers 2½″–3″ long, anthers 1″–1¼″ long. | 3. | P. Nuttallii. | |||||||||
| • | Leaves linear, rarely 1″ wide; staminate spathe 1″–1½″ long; anthers about ½″ long. | |||||||||||
| • | Leaves 5″–10″ long; sepals and petals ¾″–1″ long. | 2. | P. angustifolia. | |||||||||
| • | Leaves 2½″–4″ long; sepals and petals ½″–¾″ long. | 4. | P. minor. | |||||||||
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2.0 edit
2. Vallisnèria L. Sp. Pl. 1015. 1753.
Aquatic dioecious submerged perennials, with long grass-like floating leaves. Staminate flowers with a 2-3-parted spathe on a short scape, numerous, nearly sessite on a conic receptacle; perianth 3-parted; stamens generally 2 (1-3). Pistillate flowers on a very long flexuous or spiral scape, with a tubular, 2-cleft, 1-flowered spathe; perianth-tube adnate to the ovary, 3-lobed and with 3 small petals; ovary 1-celled with 3 parietal placentae; stigmas 3, nearly sessile, short, broad, 2-toothed with a minute process just below each sinus; ovules numerous, borne all over the ovary-wall, orthotropous. Fruit elongated, cylindric, crowned with the perianth. [Named for Antonio Vallisneri, 1661-1730, Italian naturalist.]
A genus consisting of 2 species, the one of wide distribution both in the Old World and the New, the other confined to the Gulf States. Type species : Vallisneria spiralis L.