426 



DICOTYLEDONES. 



with valvate aestivation ; the 5 petals twisted in the bud and united 

 V7ith one another at the base, and by the 5 apparently numerous 

 stamens (Figs. 445, 448), with the filaments united into a tube, with 

 reniform bilocular anthers opening by a crescentic slit (in 2 valves). 

 Carpels 3 oo united into onegynceceum ; the embryo is curved and 

 the cotyledons are folded (Figs. 447, 451) ; endosperm scanty, often 

 mucilaginous. Most of the plants belonging to this order are' 

 herbs, often closely studded with stellate hairs. The leaves are 

 most frequently palmatifid or palmatisect. 



An epicalyx is often found formed by floral-leaves placed close beneath the 

 calyx, in some 3, in others several. The median sepal is posterior in the 

 species without epicalyx, often anterior in those which have an epicalyx. The 

 petals are twisted either to the right or to the left in accordance with the spiral of 

 the calyx ; they are most frequently oblique, as in the other plants with twisted 

 corollas, so that the portion covered in the aestivation is the most developed. 

 The corolla drops off as a whole, united with the staminal tube. Only the 5 

 petal-stamens are developed, but they are divided into a number of stamens, 

 placed in 2 rows, and provided only with half- anthers (leaf-segments, see Fig. 

 446; the sepal- stamens are completely suppressed) ; these 5 staminal leaves 

 are then united into a tube, frequently 5-dentate at the top, and bearing the 



FIG. 415. Longitudinal section throu3a the 

 flower of Malva silvestris. 



FIG. 446. Diagram of Althcea rosea ; 

 i the epicalyx. 



anthers on its external side. The pollen-grains are specially large, spherical 

 and spiny. There are from 3 to about 50 carpels united into one gynoeceum and 

 placed round the summit of the axis which most frequently projects between 

 them. There is only 1 style, which is generally divided into as many stigma- 

 bearing branches as there are carpels (Figs. 445, 448). The fruit is a schizo- 

 carp or capsule. Endosperm (Figs. 447 A, 451) scanty, often mucilaginous 

 round the embryo, which is rich in oil. 



The order is the most advanced type of Columniferas ; it stands especially 

 near to the Sterculiaceae, but is separated from these and from the Tiliaceae, 

 among other characters, by its 2-locular (ultimately 1-chambered) anthers. 



The sub-orders may be arranged as follows : 



