An Illustrated Flora of the Northern United States, Canada and the British Possessions/Hydrocharitaceae
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Aquatic or mud-inhabiting herbs, with broad or narrow leaves borne on a very short stem. Flowers regular, monoecious or dioecious, arising from spathes of distinct or united bracts. Perianth superior, 6-parted, the segments usually all petaloid, the flower-tube adnate to the ovary in the pistillate flowers. Stamens 6-12, distinct or monodelphous. Ovary visually 6-9-celled. Styles 6-9. Ovules numerous. Fruit somewhat fleshy, usually indehiscent. Seeds numerous.
About 8 genera and 20 species, in temperate and tropical regions. Thalassia in Florida.
1. Limnòbium L. C. Richard, Mem. Inst. Paris, 32: 66. pl. 8. 1811.
Aquatic, stoloniferous herbs, the leaves fascicled at the nodes, petioled, broad, cordate. Flowers monoecious, white, arising from sessile or stipitate, 2-leaved, membranous spathes. Perianth 6-parted ; segments petaloid, the 3 outer oblong to oval, the 3 inner oblong to linear. Staminate flowers 2-4 in a spathe, long-penduncled, the stamens united in a column bearing 6-12 anthers at different heights, sometimes producing only 9-12 staminodia, the filaments tipped with abortive anthers. Pistillate flowers sessile or short-peduncled with 3-6 vestigial stamens; ovary 6-9-celled with as many central placentae; stigmas as many as the cells, each 2-parted. Fruit a many-seeded berry. [Greek referring to the aquatic habitat.]
Species, 3 or 4, natives of America. Type species: L. Bosci L. C. Richard, the same as the following.
|1. Limnobium Spóngia (Bosc.) L. C. Richard.
Frog's-bit. Fig. 253.
Hydrocharis cordifolia Nutt. Gen. 2: 241. 1818.
H. Spongia Bosc, Ann. Mus. Paris, 9: 396, pl. 30. 1807.
Limnobium Spongia L. C. Richard, Mem. Inst. Paris, 32:66. pl. 8. 1811.
Limnocharis Spongia L. C. Richard ; Steud. Nomencl. Ed. 2, Part 2, 45. 1841.
Blades of the leaves orbicular or broadly ovate, cordate or reniform, faintly 5-7-nerved and cross-veined, purplish and spongy beneath, 10″–2′ broad, on petioles 1′–10′ in length. Stolons rooting and sending up flowers and leaves at the nodes; peduncles of the staminate flowers 3′–4′ long, those of the pistillate flowers stouter, 1′–2′ long, nodding in fruit.
In shallow, stagnant water, Lake Ontario, to Florida, west to Illinois, Missouri and Texas. July-Aug.