BRACTS AND FLORAL LEAVES. 8I 
corolla only are as a rule considered, eg., the andreecium and 
gyneecium of a radially symmetrical flower may or may not agree 
with the general symmetry. 
The floral receptacle, like the receptacle of a shortened flower 
cluster, may exhibit considerable diversity of form (fig. 37). If 
it is elongated, conical, or flattened, the flower is said to be hypo- 
gynous, 7.¢., the andreecium, corolla, and calyx evidently grow 
from a region below 
the gynecium, or at 
any rate do not start 
from a higher level 
(fig. 37, A). But the 
receptacle may cease 
growing at the centre 
but not at the edges, 
when it forms a cup- 
like structure, on the 
rim of which andre- 
cium, corolla, and calyx 
are situated. Two con- 
ditions are here dis- 
tinguishable. Hither 
the gynecium remains 
free, and can readily 
be dissected away from 
the receptacle, or else 
it becomes inseparably 
fused with this. In 
the former case (fig. Fig. 37.—Relation of Parts of Flower [after Prantl]. A, 
= B, C. diagrams of longitudinal sections of hypogynous, 
375 B) the flower is perigynous, and epigynous flowers. Floral receptacle 
oy ti dotted in A and B; in C the inner half of dotted part 
termed perigynous, be is wall of ovary, the outer half is receptacle; ca. 
cause the floral leaves calyx; co. corolla; an. stamens; gz. pistil; ov. in- 
external to the gyna- = Tet ove. 
cium grow on a ridge round about it; in the latter (fig. 37, C), 
epigynous, since they appear to grow upon it. Buttercup, rose, 
and fuchsia are good examples of hypogynous, perigynous, and 
epigynous respectively. 
In the buttercup, as we have seen, the perianth leaves are 
arranged in whorls, and the stamens and carpels in a spiral. 
Such a flower is called hemicyclic, because a part only of its leaves 
are arranged in whorls (cycles). Departure from this type may 
take place in two directions. On the one hand, an acyclic flower, 
like the white waterlily, has all its parts in a spiral; on the 
other hand, a cyclic Hower has all its parts arranged in whorls, 
as may be seen in stonecrop and white lily (fig. 38). 
F 
