An Illustrated Flora of the Northern United States, Canada and the British Possessions/Vallisneriaceae

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.

Stem branched ; leaves whorled or opposite. 1. Philotria.
Acaulescent ; stoloniferous ; leaves grass-like, elongated. 2. Vallisneria.


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.

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.


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.