: DICOTYLEDONS 207 
are reduced forms, but this cannot be taken for granted, 
and further investigation is needed before definite con- 
clusions can be reached as to their systematic position. 
The Amentacee are largely inhabitants of the cooler 
parts of the world, some of them, like the willows and 
Fia. 50 Or eee —A, section of the flower of a buttercup (Ranun- 
culus) ; the numerous carpels are entirely separate; B, flower of wild 
columbine (Aquilegia) ; the petals, p, are modified into tubular necta- 
ries; C, flower of a larkspur (Delphinium); the flower is strongly 
zygomorphic, and the two upper sepals form the spur, or nectary; D, 
flower of the tulip-tree (Liriodendron), one of the Magnolia family; 
the flower is divided lengthwise to show the numerous stamens, and 
the separate carpels grouped together upon the elongated central recep- 
tacle; E, flower of the wild lotus (Nelumbo), one of the water-lily 
family; F, young fruit of the lotus, consisting of the enlarged conical 
receptacle, with the separate carpels, car, embedded in cavities in its 
upper surface. 
birches, being among the most northerly of all trees and 
shrubs. 
A second primitive group of Choripetale is the 
Polycarpice represented by the buttercup family and 
its allies. Some of these also recall one group of the 
Monocotyledons, the Apocarpe, eg. Alisma, Sagitta- 
