264 HYDROCHARTDACEiE. Hydrocharis. 



petiolate ; the lamina 1-2 inches in diameter, with about 5 primary nerves which curve from 

 the base towards tiie apex, and are connected by horizontal veins ; ihe under surface often 

 purplish, and the central part lacunose-reticulated, the sinus at the base deep or almost wanting. 

 Spathes hyaline. Peduncle of the sterile flower about 3 inches long. Sepals oval, green. 

 Stamens about 12: filaments united into a short thick column : anthers linear. Peduncle of 

 the fertile flower an inch and a half long, thick. Ovary oblong : stigmas apparently 1-2 - 13, 

 but rather 6-7, which are very deeply parted ; the segments papillose-fibrillose. Ovules 

 numerous, orthotropous. 



Braddock's bay, near Lake Erie, Greece, Monroe county (Dr. S. B. Bradley). Fl. August. 

 I have adopted Mr. Nuitall's name, because Bosc's is inappropriate. The description here 

 given is taken from imperfect specimens sent by Dr. Bradley, and I have no better from any 

 part of the country. 



2. UDORA. Nutt. gen. 2. p. 242; Endl. gen. 1206. VDORA. 



[From the Greek, hydor, or udffr, water; its place of growth.] 

 Flowers polygamous (dioecious, Nutt.; perfect, Endl.), solitary, from a tubular bifid spathe. 

 Perianth 6-parted, petaloid. Sterile fl. Stamens 9 : anthers oval, nearly sessile. 

 Perfect fl. Tube of the perianth produced above the ovary into a very long slender 

 tube. Stamens 3 - 6 : filaments short, subulate : anthers oblong, innate ; the cells parallel, 

 distinct. Ovary oblong, one-celled, with 3 projecting parietal placentae, which in the upper 

 part meet in the centre : ovules orthotropous,* ascending. Style long and filiform, cohering 

 with the tube of the perianth : stigmas 3, large, spreading, oblong-cuneiform, 2-lobed, 

 papillose. Fruit (immature) oblong, coriaceous, few-seeded. Seeds elliptical, smooth. — 

 A submersed aquatic, with verticillate serrulate leaves and minute flowers. 



1. Udora Canadensis, Nutt. (Plate CXXV.) Little Water Snakeweed. 



Nutt. I. c; Beck, hot. p. 342 ; Darlingt. fl. Cest. p. 570. U. verticillata, Hook. ft. Bor.- 

 Am. 2. p. 193. Elodea Canadensis, Michx. fl. I. p. 20 ; Torr. compend. p. 376. Serpicula 

 verticillata, Muhl. cat. p. 84. S. occidentalis, Pursh fl. I. p. 33. 



Perennial ? Stem dichotoinously much branching, slender. Leaves usually verlicillate in 

 threes, sometimes in fours, or the lower ones opposite, varying from oblong-ovate to lanceolate- 

 linear, acute or obtuse, finely serrulate, one-nerved. Flowers axillary ; the sterile ones on a 

 separate plant, minute, sessile, usually breaking ofT connection with the parent plant, when 

 they float on the surface of the water, and the granular pollen escapes. These grains consist 



* "Ovules anatropous," Endl.; but they are certainly orthotropous in our plant, and so they are clearly represented in 

 the plate of the nearly allied Lagarosiphon of Harvey in Hook. jour. bot. t. 22, but which in the description (by inadver- 

 tence 1 ) are called anatropous ! 



