MONANDRIA. DIOYNIA. 3 



Ifintica, p. 2. observes also that there are 1 or 2 stamens 

 in this genus. 



4. HIPPURIS. L. (Mare's-tail.) 



Calix obsolete, entire, above the seed. Corol- 

 la 0. SUjle received in a groove of the antlier! 

 (stamen seated upon the style?) Stigma simpkv 

 Seed 1. 



Habitus. Stem cvlindric, simple; leaves verticillate, 

 entire; flowers around the axill. 



Species. 1. }J. viiJgaria? but the leaves are mostly by 

 sixes in the European plant, not by eights (in fresh watei* 

 ponds and diiches; rare). The //. marilima of Sweden and 

 Finland grows on the sea-cuast. 



Obs. The Hii^puris appears to be the simplest ph^eno- 

 garrtotis pb.nr m nalui-c; and stands ^'ilbout any dislinct 

 affinities to other genera. 



Order 2. — Digyxia. 



5. CALLITRICHE. L. (AYa tor- star.) 



Calix inferior, 2-Ieaved. Corolla 0. Seeds 4^ 

 naked, compressed. 



Leaves opposite, flowers axillary, (In C. verna monoi- 

 cous.) 



Species. 1. C. verna. 2- aiitiimnaUs? The C. verna\% re- 

 markably polymorphous, the leaves vary from the places 

 where they grow; sometimes it produces 2 stamen:j, and 

 in some instances the flowers are hermaphrodite. The 

 leaves of the calix are described by Desfontames as be- 

 ing concave, and iunate, v.'ith the filament as long as the 

 calyx; in the American plant, fC. heteropJuUa of Pursh,) 

 the stem is compressed, and bifistulous, for floatincr; -hf. 

 lower branches with narrower and oft<-n emarginated 

 leaves, producing only male or female flowers, the central 

 branches wiih retus«=', spa'huiate oval, o-nerved leaves, 

 bearing tliose which are i.ermaphrodite, with the stamena 

 much exserted. 



6. CORISPERMUM. L. (Tick seed.) 



Calix a-parted. Corolla 0. Seed 1, plano-con- 

 vex, oval, and naked, with an acute circular 

 margin. 



