This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
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.
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.