46 ELODEACEAE 



as long as the body ; facial wings prominent, 1 on each side. [/ longirostra australis J. 

 G. Smith.] 



In low grounds, Alabama. Summer. 



20. Sagittaria Engelmanniana J. G. Smith. Slender, monoecious, glabrous. Leaf- 

 blades narrow, 8-20 cm. long, shorter than the petioles ; lobes linear, 1-5 mm. broad, the 

 terminal and basal about equal in length : scapes about as tall as the leaves, 2-6 dm. long : 

 whorls of inflorescence 5-6, remote : bracts lanceolate, 8-12 mm. long : pedicels ascend- 

 ing, those of staminate flowers often longer than those of the pistillate : sepals ovate, 6-7 

 mm. long, acute : filaments not dilated, glabrous : mature fruiting heads subglobose, 12-14 

 mm. in diameter : achenes obovate, 4 mm. long ; beak erect, J-J as long as the body ; facial 

 wings 1-3. 



In shallow water, Massachusetts to Florida. Summer. 



21. Sagittaria latif olia Willd. Monoecious or dioecious. Leaf-blades ample, some- 

 times broader than long, 15-40 cm. long, glabrous and rarely pubescent ; basal lobes ovate 

 or lanceolate, acute or acuminate : scape 3-6 dm. long, angled : bracts 1-5 cm. long, gla- 

 brous, acute or acuminate : whorls of the inflorescence mostly distant: pedicels variable, 

 those bearing pistillate heads 2-5 cm. long, or longer : filaments not dilated, glabrous : 

 mature fruiting heads subglobose, 1.5-3 cm. in diameter : achenes obovate, about 3 mm. 

 long, erect, undulate ; beak ascending or recurved. 



In swamps and shallow water, New Brunswick to British Columbia, Florida and Louisiana. Sum- 

 mer and fall. 



22. Sagittaria pub6scens Muhl. Monoecious or dioecious, puberulent or hirsute. 

 Leaf-blades oblong or broadly ovate, 8-25 cm. long, usually abruptly pointed ; basal lobes 

 ovate to lanceolate, about ^ as long as the blade or longer : scapes 3-6 dm. tall : whorls of 

 the inflorescence remote : pedicels variable in length, surpassing the bracts : bracts ovate 

 or suborbicular, obtuse, 7-10 mm. long: mature fruiting heads 8-15 mm. in diameter: 

 achenes somewhat anvil-shaped or resembling the head of a bird, 2-3 mm. long ; beak 

 horizontal or somewhat declined. 



In meadows or marshes, Ontario to Florida and Alabama. Summer and fall. 



23. Sagittaria Montevid6nsis Cham. & Schlecht, Monoecious, robust. Leaf -blades 

 sagittate, 1-5 dm. long, often as broad, glabrous above, sparingly scabrous on the nerves 

 beneath ; basal lobes acute or acuminate, more or less divergent, middle lobe acute : scapes 

 sometimes 6-8 cm. thick at the base, usually simple : whorls of the inflorescence several or 

 numerous, 2-4 of the lower ones pistillate : bracts lanceolate, acuminate, united below : 

 pedicels of staminate flowers slender, 2-3 cm. long, surpassing those of pistillate flowers : 

 sepals 10-15 mm. long, obtuse : petals white, obovate : filaments not dilated, glandular- 

 pubescent, longer than the anthers : mature fruiting heads 1.5-3 cm. in diameter : achenes 

 2-3 mm. long, rhomboid-obovate, winged ; beak slender, oblique ; faces flat. 



In swamps, North Carolina to Alabama and California, naturalized from South America. Spring 

 and fall. 



Order 4. HYDROCHARITALES. 



Floating or more or less emersed herbs, perennial by rootstocks or stolons. 

 Leaves usually with dilated blades. Flowers monoecious or dioecious, arising 

 from spathes. Perianth of 2 dissimilar series, or the corolla rarely wanting. 

 Androecium of 3-12 stamens. Gynoecium of 3-15 united carpels. Ovary in- 

 ferior, with several parietal placentae or several -eel led. Endosperm wanting. 



Ovary 1-celled, with 3, or rarely 2, 4 or 5 parietal placentae : stigmas usually 3. 



Fam. 1. EI.ODEACEAE. 

 Ovary 6-9-celled : stigmas 6-9. Fam. 2. HYDROCHARITACEAE. 



FAMILY 1. ELODEACEAE Dumort. TAPE-GRASS FAMILY. 



Floating or submerged sometimes acaulescent herbs, perennial by root- 

 stocks or stolons. Leaves clustered or remote : blades short and broad or much 

 elongated and ribbon-like. Flowers monoecious or dioecious, arising from a 

 spathe or 1-3 bracts. Perianth regular, of 3 sepals and 3 petals, or the latter 

 wanting, all more or less petaloid. Androecium of 3-12 stamens. Filaments 

 distinct or monadelphous. Anthers 2-celled. Gynoecium a single pistil. Ovary 

 inferior, 1-celled with 3 or rarely 2-5 parietal placentae. Ovules mostly num- 

 erous, orthotropous or anatropous. Fruit usually indehiscent, often becoming 



