HETEROGAMY. 19] 
tually suppressed, a tendency towards structural com- 
pleteness rather than the reverse. It must be also 
understood that the following remarks apply to struc- 
tural points only, and are not intended to include 
the question of function. The occurrence of hetero- 
morphic unions renders it necessary to keep in mind 
that plants hermaphrodite as to structure are by no 
means necessarily so as to function. 
The simplest case of this alteration in the relative 
position of the sexes is that which occurs in moncecious 
plants, where the male and female flowers have a definite 
position, but which in exceptional instances is altered. 
Change in the relative position of male and female flowers 
may thus occur in any moneecious plant. Cultivated 
maize, Zea Mays, frequently exhibits alterations of this 
kind; under ordinary circumstances, the male inflor- 
escence 1s a compound spike, occupying the extremity 
of the stem, while the female flowers are borne in 
simple spikes at a lower level, but specimens may now 
and then be found where the sexes are mixed in the 
same inflorescence; the upper branching panicle 
usually containing male flowers only, under these 
circumstances, bears female flowers also.’ In like 
manner, but less frequently, the female inflorescence 
occasionally produces male flowers as well. 
Among the species of Carex it is a common thing 
for the terminal spike to consist of male flowers at the 
top, and female flowers at the base; the converse of 
this, where the female flowers are at the summit of the 
spike, is much more uncommon. An illustration of 
this occurrence is given in the figure (fig. 100). 
Among the Conifere numerous instances have been 
recorded of the presence of male and female flowers 
on the same spike, thus Mr. now Professor Alexander 
Dickson exhibited at the Botanical Society of Edinburgh 
' See also Clos., ‘Mem. Acad. Toulouse,’ sixth ser., t. iii, pp. 294—305. 
Scott, ‘Trans. Bot. Soc. Edinburgh,’ t. viii, p. 60. Wigand, ‘ Flora,’ 
1856, p. 707. 
