SPERMATOPHYTES : ANGIOSPERMS 
like small foliage leaves, and the inner set (corolla) becom- 
ing more delicate in texture, larger, and generally brightly 
colored (Fig. 71). 
2. From spiral to cyclic flowers. In the simplest flowers 
the sporophylls and floral leaves (if any) are distributed 
about an elongated axis in a spiral, like a succession of 
leaves. As this axis is elongated and capable of continued 
growth, an indefinite number of each floral organ may ap- 
pear. The spiral arrangement and indefinite numbers, 
therefore, are regarded as primitive characters. 
In higher forms the axis becomes shorter, the spiral 
closer, until finally the sets of organs seem to be thrown 
into rosettes or cycles. These cycles may not appear in all 
the organs of a flower, but finally, in the highest forms, all 
the floral organs are in definite cycles. All through this 
evolution from the spiral to the cyclic arrangement there 
is constantly appearing a tendency to " settle down " to 
certain definite numbers, and when the complete cyclic 
arrangement is finally established these numbers are estab- 
lished, and they become characteristic of great groups. 
For example, in the cyclic Monocotyledons there are nearly 
always just three organs in each cycle, while in the cyclic 
Dicotyledons the number five prevails. 
3. From hypogynous to epigynous flowers. In the sim- 
pler flowers the sepals, petals, and stamens arise from be- 
neath the ovary or ovaries (Fig. 72, ./), and as in such cases 
the ovary may be seen distinctly above the origin (inser- 
tion) of the other parts, such a flower is often said to have 
a " superior ovary," or to be hypogynous, meaning in effect 
" under the ovary," referring to the fact that the insertion 
of the other parts is under the ovary. 
There is a distinct tendency, however, for the insertion 
of the outer parts to be carried higher up, until finally it is 
above the ovary, and sepals, petals, and stamens seem to 
arise from the top of the ovary (Fig. 72, 5), such a flower 
being epigynous. In such cases the ovary does not appear 
