ORDER L. ONAGRACEiE. 317 



base into a slender petiole. Flowors axillary, sessile ; segments of tlio 

 calyx very short. — lied. If. Through the summer. In water. 



13. L. xa'taks, (Ell.) Stan glabrous, somewhat fleshy, creepin;^ or 

 floating. Leaves opposite, ovate-spalulate, tapering into a petiole ; 

 lower ones nearly sessile. Flowers axillary, sessile ; segments of the 

 calyx triangular-ovate. Petals sometimes wanting. Capsule quadran- 

 gular, attenuate at the base. — Yellow. If. July — Oct. In swamps. 

 Middle Car. and Geo. 



14. L. PEDUNCULo'sA, (Mich.) Stem creeping, glabrous, branching. 

 Leaves opposite, sessile, lanceolate, entire ; upper surface glabrous, the 

 under sprinkled with hairs. L'loivers axillary, solitary, on long pedun- 

 cles. Petals obovate, entire, caducous ; segments of the calyx linear- 

 lanceolate, acuminate, spreading. Capsule obconic, pubescent. — Yellow. 

 2f . May — June. In wet places. Stem 3 — 10 inches. 



Genus VI.— PROSERPINA'CA. L. 3—3. 

 (From proserpo, to creep ; creeping plants.) 



Calyx 3-parted ; tube 3-sided. Petals 3 or none. Stamens 

 3. Stigmas papillose. Fruit 3-sided, 3-celled. Steins creep- 

 ing. Leaves alternate. Flotvers axillary. Aquatic herbs. 



1. P. palus'tris, (L.) Root fibrous. Stem herbaceous, procumbent, 

 columnar, branching, glabrous, colored. Leaves sessile, lanceolate, 

 sharply serrate ; the lower ones pectinate or pinnatifid, glabrous. 

 Flowers 1 — 3, axillary, nearly sessile ; segments of the calyx lanceolate, 

 persistent. Fruit triquetrous. — If. April. In shallow waters. 



2. P. pectina'cea, (Lam.) Stem herbaceous, erect, sometimes branch- 

 ing, angled near the summit. Leaves glabrous, pectinate; segments 

 linear-subulate. Flowers 1 — 3, nearly sessile. jShit triquetrous, with 

 jobtuse angles. 2f . May — April. In shallow water. 2 — 8 inches. 



Genus VII.— MYRIOPHYL'LUM. Vaill. 19—12. 



(From the Greek murios, a myriad, and phulloiiy a leaf, in allusion to its numorous 



leaves.) 



Flowers perfect or monoecious. Calyx 4-parted. Petals 4 

 or none. Stamens 4 — 8. Ovary 4-celled Fruit of 4 indeliis- 

 cent carpels, cohering by the inner angles, adhering to the tube 

 'of the calyx. Aquatic plants. The submersed leaves pinnate, 

 with filiform segments. Flowers sessile, axillary, the upper 

 staminate, the middle perfect, the lower fertile. 



1. M. veuticilla'tum, (L.) Stem long, branching. Leaves verticillate ; 

 the upper pectinate, pinnatifid, the lower pinnate, with capillary seg- 

 ments. Flowers axillary, octandrous. — 1i. July — Sept. In ponds 

 and streams. Water Milfoil. 



2. M. hetkropuyl'lum, (Mich.) Stem thick, branching, terete, float- 

 ing ; the upper leaves oval, acutely serrate ; submersed leaves numer- 

 ous, veiticillate, pinnate, with setaceous segments. i'Vowrra hexandrous, 

 in irregular whorls. Cahjx with minute lobes. Petals minute. Sta- 

 mens 4 — 6. Carpels roughened, cohering at the axis. — Purple. U- 

 June- -Sept In ponds and streams. 1 — 2 feet. 



