PROVISIONS FOR ATTRACTING INSECTS 91 



The latter must be considered individually. The former are two — 

 namely, through the agency of the wind and through that of insects 

 (or occasionally other animals). 



Anemophilous and Entomophilous Flowers. — Flowers adapted to the 

 former methods are called Anemophilous; those adapted to the latter 

 are called Entomophilous. Occasionally the flower is so formed that 

 the movement of the water during rains, or in streams, effects pollina- 

 tion. 



Provisions in Anemophilous Flowers. — The activity of the wind being 

 beyond the control of the flower, the adaptation of the structure of an 

 anemophilous flower is limited to securing the benefits of such action 

 when it comes into play. This consists chiefly in (1) a gregarious habit 

 — the growing together in great numbers of individuals of one kind, as in 

 the case of grasses and of most of the forest trees of temperate latitudes; 

 (2) a very abundant pollen (.3), which is loosely fixed, one method 

 being illustrated by Fig. 267, light and easily 

 removed and transported; and (4) the dispo- 

 sition of the ovule of gymnosperms, and the 

 form and disposition of the stigma and con- 

 nected parts of angiosperms, so as to catch 

 the pollen. All these provisions may be 

 readily seen to affect the process in the case 

 of Pinus palustris, for example. In this 



, , ,, . . in I^'S- 267. Anemophilous flower of 



plant the pollen-grams contam several cells, ^ grass. 



all but one of them empty, thus decreasing 



their specific gravity. They are produced in such great abun- 

 dance that the crop, carried by strong winds, has been known to 

 fall at a great distance as a thick deposit, the so-called "sulphur- 

 showers" of history. The trees are densely massed, to the exclusion 

 of almost all others, and bear innumerable cones (Fig. 360), each 

 consisting of numerous scales, outwardly fiaring, and so disposed as 

 to catch many of the pollen grains and guide them downward to the 

 little pockets at their bases. 



Provisions in Entomophilous Flowers. — In entomophilous flowers, such 

 provisions as above described for the utilization of the pollen-carrying 

 forces, must be preceded by others of a different nature, calculated to 

 first set in motion and attract these forces. 



Provisions for Attracting Insects. — ProA'isions for attracting external 

 agents are found chiefly in the form, coloration, and size of the flower 

 or of one or more of its parts, the production of fragrant and nutriti\-e 



