124 NATURAL HISTORY OF PLANTS. 



superposed to three leaves of the calyx, each being formed of four 

 cells representing, perhaps, a pair of anthers. The prsefloration of 

 the sepals is valvate or nearly so in the male- flowers, imbricated 

 in the female, and in the intervals three petaloid pieces are seen, 

 representing a disk similar to that of Mercurialis. Hasskarlia, formed 

 of shrubs from tropical Western Africa, has the male flowers of 

 Tetrorchidium, the male sepals being clearly valvate. It differs 

 only from the latter genus by the petaloid pieces of its female disk, 

 •which alternate with the ovary cells instead of being opposite to 

 them, the cells themselves alternating with the sepals in Tetror- 

 chidium, whUe they are superposed in Hasskarlia. 



Acalypha (fig. 185-189), which has often served as the type of a 

 tribe of this family, to which it yet gives its name, is easily dis- 



Acalypha phleoides. 



Fig. 185. Moriferous branch. Kg. 186. Stamen (^°). 



tinguished by its male flower with four valvate sepals, by its 

 diplostemonous androceum, and the worm-shaped form of the 

 anther cells attached on each side towards the summit of the fila- 

 ment, and more or less elongated and folded upon themselves in the 

 bud (fig. 186-187). The female flowers, having three or four imbri- 

 cated sepals, are also remarkable in most cases on account of the 

 accrescent dentate bracts which accompany them, and by the great 

 development of the ramified style-branches. This genus consists of 

 herbaceous suffrutescent and frutescent plants from all hot regions. 

 Alchornea^ consisting of woody plants from all tropical and sub-tro- 

 pical regions, has nearly the same floral organisation, a valvate 

 calyx in the male flower with two or three divisions, and an 

 imbricated one in the female with from four to six divisions, 



