THE FLOWER (. REDUCTION, ETC.) 69 
(and even then perhaps in the derived cases) are probably largely 
connected with nutrition and correlated variation, and their value to 
the plants possessing them is problematical 1 . 
Reduction in number of Sporophylls, and Ar= 
rangement of Floral Leaves in Whorls , are two widely 
spread features of the more highly evolved flowers. The 
aggregation of sporophylls to form flowers causes many 
spores to be formed near together; the advantages of this 
were pointed out on p. 66. As means of pollination 
improve in flowers, the number of sporophylls and sporangia 
need not be so great as in the more primitive forms, and in 
general we find it smallest in the most highly specialised 
flowers. Many of the lower types of flower now existing, 
e.g. in Ranunculaceae and other orders of the Ranales, have 
their sporophylls, and often their perianth-leaves, spirally 
arranged on the axis, but in most flowers they are in whorls 
and the axis is correspondingly shorter. The members of 
any whorl usually alternate with those of the next, but 
sometimes are opposite to them, or of different number. 
The lower existing types of flowers have many stamens 
and carpels, the higher have generally two whorls of the 
former and one of the latter, and this whorl, too, is usually 
reduced in number. A very common case is for the outer 
whorls to be of 5 members each, the carpellary whorl of 
3 members or even fewer. In the Sympetalae all but the 
lowest have only one whorl of stamens, and usually only two 
carpels, or even one. The number of ovules is commonly 
reduced also in the highest types of entomophilous flowers ; 
the Compositae, for instance, show only one in each flower. 
In anemophilous flowers the number of ovules is usually 
small, perhaps because of difficulty in pollination. Other 
plants of high type, again, e.g. Orchids, find an advantage 
in numerous ovules (and compare Labiatae with Scrophu- 
lariaceae). 
Descriptive Terms , drc. Flower with leaves all spirally arranged, 
acyclic , all in whorls, cyclic , part in spirals, part in whorls, he?jiicyclic ; 
whorled, with the same number of organs in every whorl, eucyclic (the 
whorls, or flower, isomerous ), with different numbers, heterocyclic 
(whorls, or flower, hetero- or aniso-?nerous , the whorls with fewer organs 
1 Willis, On Gynodicecism &c. 3 papers in Proc. Camb. Phil. 
Soc., 1892-3. 
