244 HALORAGEiE. ' Hippuris. 



8. HIPPURIS. Linn. ; Endl. gen. 613^1. MARESTAIL. 



[From the Greek, hippos, a horse, and oura, a tail.] 



Border of the calyx very narrow and entire. Petals none. Stamen solitary, inserted on the 

 margin of the calyx. Style filiform, stigmatose on one side, at first placed between the two 

 lobes of the anther. Fruit one-celled, one-seeded. — Aquatic perennial herbs, with simple 

 stems, verticillate entire leaves, and axillary minute flowers which are often polygamous. 



1. Hippuris vulgaris, Linn. Common Marestail. 



Leaves in whorls of 8 - 12, linear, callous at the tip (Hook.). — Linn. sp. 1. p. 4 ; Engl, 

 hot. t. 763 ; Michx. Jl. I. p. I ; Pursh, fl.l.p.3; Torr.fl. I. p. 2; DC. prodr. 3. p. 71 ; 

 Hook. fl. Bor.-Am. 1. p. 217; Torr. ^ Gr. fl. N. Am. 1. p. 531. 



Stem usually a foot or eighteen inches high, jointed. Leaves about a line wide ; those on 

 the emersed part of the stem scarcely an inch in length ; the submersed ones much longer, 

 and crowded. Flowers inconspicuous ; the free portion of the calyx forming a very narrow 

 border at the summit of the ovary. Filament short and flat : anther large, red ; the two lobes, 

 when young, folded around the style which passes between them. Fruit small, somewhat 

 drupaceous ; the endocarp cartilaginous. 



Ponds and lakes. Cayuga lake {Dr. Jed. Smith) ; near Schenectady {Dr. Beck) ; ditches 

 near Coldspring, Putnam county {Prof. Bailey). It appears to be identical with the European 

 plant. 



Group 14. Ovary compound, one-celled, with parietal placent(E. Petals and stamens 

 inserted in the throat of the calyx. Flowers perfect. Calyx adherent to the 

 ovary. 



Order XLII. CACTACE^. Juss. The Cactus Tribe. 



Calyx consisting of numerous imbricated sepals, which cohere with and crown 

 the ovary, or cover its whole surface ; the inner ones confounded v^dth the 

 numerous petals. Stamens numerous, cohering with the base of the petals, 

 and inserted with them into the throat of the calyx. Ovary fleshy, one-celled, 

 with numerous parietal placentae : ovules numerous : styles united : stigmas 

 as many as the placentae. Fruit a berry, 1-celled, many-seeded ; the seeds 



