Just as we have male and female in the animal world, so we 
have male and female in the plant world. A few of our trees, 
as the Locust, Basswood and Cherries have perfect flowers, bear- 
ing both stamens and pistil. The great majority, however, have 
unisexual flowers, bearing stamens or pistils, but not both. When 
both male and female flowers are found on the same tree, the 
flowers are said to be monoecious, and when male flowers occur 
on one tree and the female on a different tree, the flowers are 
said to be dioecious. The Cottonwood is dioecious, and the 
little seeds are surrounded by a tuft of long, white hairs which 
enables the wind to carry them to considerable distances from the 
parent tree, to the disgust of people living within range. Many 
cities forbid the planting of Cottonwood on account of the 
V. TYPES OF INFLORESCENCES 
BBV Vy 
Spike. Raceme. Panicle. Corymb. Umbel. 7 Cyme. 
“cotton.” Since in some cases it is desirable to plant this rapid- 
growing tree, as in cities burning large amounts of soft coal, it 
is a distinct advantage to know that male trees are lacking in the 
objectionable “cotton” and may be planted safely. 
Before trees can produce fruit their flowers must be fertilized, 
i. e., pollen from the anther of a stamen must come in contact 
with the stigma of a pistil, Some flowers are self-fertilized, 
others are cross-fertilized. For a long time it was not known 
how fertilization was accomplished, but now we know that many 
insects, like the nectar-loving bees and butterflies, and in other 
cases the wind transport the pollen from one flower to another, 
often miles being traversed before the right kind of flower or a 
flower in the right stage of development is found. And many 
are the modifications of flowers to insure this transference of 
pollen. 
FRUIT.—So numerous and so varied are the forms of tree 
fruits that it would only be confusing to enumerate their various 
characters. Some fruits, as the achenes of the Poplars and Wil- 
— xIv — 
