ANGIOSPERMA: 197 
condition, but there is no evidence of such reduction 
shown by a study of their development, and they can- 
not readily be referred to any of the higher types of 
flowers. 
From the apocarpous type, 7.e. that in which the carpels 
are all distinct, the next step in the evolution of the 
flower is the development of a flower like that of the 
lilies, with the carpels united to form a compound pistil, 
usually composed of three parts. In this type, which is 
usually considered the central type of the Monocotyle- 
dons, the prevailing number of the different organs is 
three. 
From the lily type may be readily derived all the 
higher petaloideous forms, the Iridacex, the Scitaminez 
and the Orchidacee. In these there is a cohesion of cer- 
tain parts of the flower and usually a reduction in the 
number of stamens. On the whole, the orchids repre- 
sent the most highly specialized types. 
The affinities of certain other groups are not so obvi- 
ous. The grasses, palms, and aroids cannot readily be 
referred to the same series as the lilies, and it is likely 
that each of these groups has been derived directly from 
apocarpous ancestors. The palms and aroids show cer- 
tain points in common, while the latter group resembles 
in certain respects the aquatic forms, like some of the 
pond-weeds and their allies, and is probably related to 
them. 
The grasses must remain for the present very much 
by themselves. Perhaps a thorough study of their 
embryology may throw some light upon their affinities, 
which at present, it must be admitted, are very obscure. 
