208 EVOLUTION OF PLANTS 
ria, etc., in the character of the flowers. The parts of 
the flower are all separate, and in the lower members of 
the group, of indefinite number. This is well shown 
in the various species of buttercups (Ranunculus). The 
Ranunculus family also offers some interesting examples 
of specialization within a group which nevertheless 
retains a very primitive type in the arrangement of the 
floral parts. In Anemone (Fig. 55, A) and in Clematis, 
as well as other genera, the petals are quite suppressed 
or inconspicuous, while their place is taken by the large 
petaloid sepals. Some other genera, like the columbines 
(Aquilegia), larkspurs (Delphinium), and monkshood 
(Aconitum), have the parts of the flower extraor- 
dinarily modified in form, and yet retain the primitive 
completely separated carpels and numerous stamens 
(Fig. 50, B, C). These modifications of the flower are 
all intimately connected with insect-pollination, and 
many of the more specialized forms like Delphinium 
and Aquilegia are probably entirely dependent upon 
insects or humming-birds for pollination. On the other 
hand, some species of Ranunculus with inconspicuous 
flowers are always self-fertilized. Other Polycarpice 
are the water-lilies (Nympheacee, Fig. 50, E), magno- 
lias, and several other less familiar families. 
Another probably primitive group of the Choripetale 
is the order known as the Centrosperme. The lowest 
members of the series, the buckwheat family (Poly- 
gonacee, Fig. 49, E), the pig-weeds (Chenopodiacee), 
etc., have flowers which recall the peppers and some of 
the simple Monocotyledons in having the single ovule 
formed directly from the apex of the floral axis (Fig. 
49, F, 0). The higher ones have numerous ovules, 
