74 NORTH AMERICAN FLORA [VoLuME 17 
1. Hydromystia stolonifera G. Meyer, Fl. Esseq. 153. 1818. 
Limnobium stoloniferum Griseb. Fl. Brit. W. Ind. 506. 1861. 
Petioles 5-20 cm. long, triquetrous, thick below, tapering upwards; leaf-blades fleshy, 
ovate to suborbicular, 2-8 cm. long, entire, veined beneath ; scapes 2-5 cm. long; sepals 
in the staminate flowers lanceolate, spreading ; petals linear-filiform, spreading, about half 
longer than the sepals; filaments subulate, shorter than the anthers; styles according to 
Meyer 3, as long as the stamens; hypanthium in the pistillate flowers tubular; sepals 
lanceolate; petals according to Meyer 3 rudimentary scales, according to Ascherson and 
Girke wanting; styles subulate, pilose. 
TYPE LOCALITY : Stagnant water, Hamburg plantation, Essequibo [British Guiana]. 
DISTRIBUTION: Porto Rico and Lesser Antilles; also in Guiana and Venezuela. 
3. LIMNOBIUM Rich. Mém. Inst. Paris 2: 32. 1811. 
Usually floating aquatics with pendant roots and stolons, dioecious or monoecious, 
Leaves basal, clustered, petioled ; blades rounded heart-shaped, spongy-reticulate beneath. 
Staminate spathe peduncled, 1-leaved, producing 3 long-pedicelled flowers. Sepals 3, 
oblong. Petals3, linear. Stamens 6-12, monadelphous; anthers linear, unequal in height. 
Pistillate spathe 2-leaved, with a single short-pedicelled flower. Petals and sepals as in the 
staminate flowers. Stamens represented by 3-6 awl-shaped rudiments. Ovary inferior, 
6-9-celled, with as many placentae in the axis. Stigmas as many as the cells, 2-parted, 
Fruit an ovoid, 6-9-celled, many-seeded berry. 
Type species, Limnobium Bosci Rich., which is the same as L. Spongia. 
1. Limnobium Spongia (Bosc) Rich.; Steud. Nom. Bot. 
ed. 2. 45. 1841. 
Hydrocharis Spongia Bosc, Ann. Mus. Paris 9: 396. 1807. 
Limnobium Bosci Rich. Mém. Inst. Paris 2: 32. 1811. 
Hydrocharis cordifolia Nutt. Gen. 2: 241. 1818. 
Petioles erect or ascending, 5-2.5 cm. long; leaf-blades ovate to suborbicular or the 
earlier reniform, 2-5 cm. broad, obtuse at the apex, truncate or cordate at the base, entire, 
purplish beneath, becoming somewhat spongy in winter; staminate scapes 7-10 cm. long, 
filiform; spathe lance-ovoid, 3-5 cm. long; pistillate scapes about 2.5 cm. long, stout, 
recurved in fruit; sepals 7-10 mm. long, oblong; petals linear, 8-10 mm. long; anthers 
linear, about 4 mm. long; stigmas filiform, 10-15 mm. long, papillose-ciliate ; berry oval, 
1-1.5 cm. long. 
TYPE LOCALITY: South Carolina. 
DISTRIBUTION: Shallow water, from New Jersey and Ontario to Florida, Texas, Missouri, and 
Tilinois. 
ILLUSTRATIONS: Mém. Inst. Paris 2: 7.8; Ann. Mus. Paris 9: #/. 30; Britt. & Brown, II. 
FL. f. 209. 
