THE FLOWER 291 
When the pollen is transferred to the stigma of its own flower 
the process is called Close or Self-pollination; if to a stigma of 
another flower, Cross-pollination. If fertilization follows, these 
processes are termed respectively, Close or Self-fertilization and 
Cross-fertilization. Close-fertilization means in time ruination to 
the race and happily is prevented in many cases by (a) the sta- 
mens and pistils standing in extraordinary relation to each other, 
(6) by the anthers and stigmas maturing at different times, (¢) by 
the pollen in many cases germinating better on the stigma of 
another flower than its own and (d) by staminate and pistillate 
flowers being borne on different plants of the same species. 
In flowers like the geranium, clerodendron and chamomile, 
the stamens mature and shed their pollen before the stigmas are 
receptive. Such flowers are called protandrous. In the plantains, 
figworts, etc., the stigma matures before the stamens. Such 
flowers are protogynous. 
The agents which are responsible for cross-pollination are 
the wind, insects, water currents, small animals, and man. 
Wind-pollinated flowering plants are called ANEMOPHILOUS; 
their pollen is dry and powdery, flowers inconspicuous and 
inodorous, as in the Pines, Wheat, Walnut, Oak, Birch, Beech, 
Wormwood, Hop, etc. 
Insect-pollinated plants are called Enromopuitous. These, 
being dependent upon the visits of insects for fertilization, possess 
brilliantly colored corollas, have fragrant odors, and secrete 
nectar, a sweet liquid very attractive to insects, which are adapted 
to this work through the possession of a pollen-carrying appa- 
ratus. Examples: Orchids, Irises, F oxglove, Aconites, etc. 
Plants pollinated through the agency of water currents are known as 
Hypropuitous. To this class belong such plants as live under 
water and which produce flowers at or near the surface of the 
same. Some of these as Ruppia disperse floating pollen grains, 
others like Zostera produce pollen of the same specific gravity as 
water while Vallisneria, the common eelgrass, liberates floating 
male flowers. 
Bird-pollinated plants are called OrnirHopuiLous. Some 
plants like the Trumpet Creeper, Nasturtium and Honeysuckle 
are pollinated by humming birds. Other plants, as Aspidistra, 
FO Te oe ON eee 
