CLASS DKECTA. 203 



with the petals. In the fertile flowers, a germ 

 crowned with the margin of the calyx ; I stigma, and 

 a globose, 1-seeded berry. The only species indige- 

 nous to the United States is the V. verticillatum, which 

 grows as far north as the lower part of the state of 

 Delaware. In this the branches are opposite, the 

 leaves are wedge-oval, 3-nerved and obtuse; the spikes 

 axillary and solitary ; the sterile flowers mostly trifid, 

 and the berries white, adhering, when mature, to the 

 trunks of trees and their branches by means of the vis- 

 cid pulp with which they are filled. 



In Pentandria is arranged the Hop (Humulus) of 

 the natural family of the Nettles, or Uhtice^:. But 

 one species is known, a twining tall plant, growing oc- 

 casionally in alluvial soils, with opposite, 3 to 5-lobed, 

 rough leaves. — The staminiferous flowers have a 5- 

 leaved calyx. The anthers have two pores at their 

 extremity. There is no corolla. The fertile flowers col- 

 lected into aments, have a 1 -leaved, large, persistent, 

 concave, entire calyx ; no corolla ; 2 styles ; and 1 

 seed. At the base of the calyx there is produced a 

 coating of diaphanous yellow glands, soluble in warm 

 water, and to which the Hop owes all its bitterness. 

 This extractive matter has been termed Lupuline. 



The Hemp (Cannabis), also of the natural family 

 URTicEiE, has a 5-parted calyx in the staminiferous 

 flowers, and no corolla. The calyx of the fertile flow- 

 er is 1 -leaved, entire, and bursting on the side. In 

 this there are 2 styles ; and the seed is a bivalvular 

 nut within the closed calyx. There is only a single 

 species of the genus known ; occasionally cultivated 

 in the Uuited States. It is a curious fact, in the his- 

 tory of the sexual system of Linnaeus, that pistilliferous 

 plants of the hemp have been known to produce fer- 

 tile seeds when cut off from all access to the stamin- 

 iferous individual. 



