MONANDRIA. DIGYNIA. 3 



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

 in this genus. 



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



dalix obsolete, entii'e, above the seed. Corol- 

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

 (stamen seated upon the style?) Stigma simple. 

 Seed I. 



Habitus. Stem cyluidric, simple; leaves verticillate, 

 entire; flowers around the axill. 



Species. 1. //. vulgaris? but the leaves are mostly by 

 sixes in the European plant, not byeiKlits (in fresh water 

 ponds and diiches; lare) The //. maritima of Sweden and 

 Finland g-rows on t'.e sea-coast. 



Obs. The Hii)puris appears to be the simplest phaeno- 

 gamous plant in nature; and stands without any distinct 

 affinities to other genera. 



Order 2. — Digynia. 



5. CALLITRICHE. i. (Water-star.) 



Calix inferior, £-leaved. Corolla 0. Seeds 4, 

 naked, compressed. 



Leaves opposite, flowers axillary, (in C verna monoi- 

 cous.) 



Species. 1. C.verna.'2- autumnalis? The C. vema'is re- 

 markably polymorphious, the leaves vary from the places 

 where they grow; sometimes it produces 2 stamens, and 

 in some instances the flowers are hermaphrodite. The 

 leaves of the calix are described by Desfontaincs as be- 

 ing- concave, and lunate, with the filament as long as the 

 calyx; in the American plant, fC. heterofjhllla of Parsh,) 

 the stem is comprt ssed, and bifistulous, for flxiating; ^he 

 lower branches with narrower and otVn cmarginated 

 leaves, producing only male or female flowers, the central 

 branches with retuse, sjjathulate oval, 3-nerved leaves, 

 bearing those which are hermaphrodite, with the stamens 

 much exserted. 



6. CORISPERMUM. Z. (Tick-seed.) 



Calix 2-parted. Corolla 0. Seed 1, plano-con- 

 vex, oval, and naked, with an acule circulai' 

 margin. 



