226 COMMON CANADIAN WILD PLANTS. 



3. S. gramin'ea, Michx. Scape very slender, erect. 

 Leaves varying from ovate-lanceolate to linear, scarcely ever 

 sagittate. 



4. S. ealyei'na, Engelm., var. spongiosa, Engelm. 

 Scape weak, and at length usually procumbent. Fertile 

 flowers perfect. Leaves broadly halberd- shaped with wide- 

 spreading lobes. Submerged leaves without blades. Atl. 

 Prov. 



ORDER XCIX. HYDROCHARIDA'CE^E. (FROG'S-BIT F.) 



Aquatic herbs, with dioecious or polygamo-dioscious flow 

 ers on scape-like peduncles from a kind of spathe of one or 

 two leaves, the perianth in the fertile flowers of 6 pieces 

 united below into a tube which is adherent to the ovary. 

 Stigmas 3. Fruit ripening under water. 



Synopsis of the Genera. 



1. Elode'a. Growing under water, the pistillate flowers alone coming 



to the surface. Stem leafy and branching. Perianth of the fertile 

 flowers with a 6-lobed spreading limb, the tube prolonged to an 

 extraordinary length, thread-like. Leaves crowded, pellucid, 1- 

 nerved, sessile, whorled in threes or fours. Stamens 3-9. 



2. Vallisue'ria. Nothing but the pistillate flowers above the surface, 



these on scapes of great length, and after fertilization drawn 

 below the surface by the spiral coiling of the scapes. Tube of 

 the perianth not prolonged. Leaves linear, thin, long and ribbon- 

 like. 

 (In both genera the staminate flowers break off spontaneously and 



float on the surface around the pistillate ones, shedding their pollen 



upon them.) 



ELODE'A, Michx. WATEK-WEED. 



E. CanadensiS, Michx. (Anach'aris Canadensis, Plan- 

 chon.) Common in slow waters. 



2. V ALLISXE KIA, L. TAPE-G.KASS. EEL-GRASS. 



V. spira'lis, L. Leaves 1-2 feet long. Common in slow 

 waters. 



ORDER C. ORCHIDA'CEJE. (ORCHIS FAMILY.) 



Herbs, well marked by the peculiar arrangement of the 

 stamens, these being gynandrous, that is, borne on oradher- 



