HALORAGACE.E. MARE's-TAIL TRIBE. 215 



OBD. XXVIIL HALOKAGACE.E. THE MARE'S- 

 TAIL TRIBE. 



Calyx adhering to the ovary, and either expanding 

 into 3 or 4 minute lobes, or reduced to a mere rim ; 

 petals either minute and placed on the mouth of the 

 calyx, or wanting ; stamens either equalling the petals 

 in number, twice as many, or, when petals are absent, 

 1 or 2 ; ovary with one or more cells -^stigmas equal in 

 number to the cells of the ovary ; capsule not opening ; 

 seeds solitary, pendulous. An unimportant Order, com- 

 prising about 70 species of plants, which are for the 

 most part herbaceous aquatics, with inconspicuous 

 flowers often destitute of petals, and in one genus, Hip- 

 puris (Mare's-tail), composed of a minute calyx, a soli- 

 tary stamen, and a single seed. In several species the 

 stamens and pistils are in separate flowers. 



1. HIPPURIS (Mare's- tail). Calyx forming a minute, 

 indistinctly 2-lobed rim to the ovary ; petals ; stamen 

 1 ; style 1 ; seed 1, nut-like. (Name in Greek signifying 

 mares tail.) 



2. MYRIOPHYLLUM (Water Milfoil). Stamens and 

 pistils in separate flowers, but on the same plant (monoe- 

 cious) ; calyx 4-parted ; petals 4 ; stamens 8 ; styles 4 ; 

 fruit of 4 nut-like seeds. (Name from the Greek myrioi, 



10,000, and phyllon, a leaf, from its numerous leaves.) 



1. HIPPURIS (Hards-tail). 



1. H. vulgdris (Common Mare's-tail). The only 

 British species, not uncommon in stagnant water. A 

 singular plant, with erect, jointed stems, which are un- 

 branched, except at the base, and taper to a point, 

 bearing whorls of very narrow leaves with hard tips. 

 The inconspicuous flowers are sessile in the axils of the 

 upper leaves, and are often without stamens. Not to be 



