56 ORGANOGRAPnr. 



» 



stigmas are generally large, often furnished with hairs or 

 dissected into plumes (Fig. 131) for the retention of the 

 grains that may come in contact with them. The anthers 

 are often suspended on capillary filaments, so as to be more 

 directly exposed to the action of the wind. 



72. When pollination is effected by insects, the flowers 

 are said to be entomophilous (Gr. eniomon, insect; 

 philos, loving). In these the amount of pollen produced is 

 not so great, there being but little waste as compared with 

 the loss when transported by the wind. It is not so dry 

 and incoherent as in the anemophilous flowers ; the grains 



are generally moist or slightly viscid, often 

 provided with projections or entangling 

 threads. In the Orchids and Milkweeds the 

 pollen is in masses, supplied with viscid pedi- 

 cels (Fig. 148). All these contrivances tend 

 to insure the adherence of the pollen grains 

 or masses to the head, legs, or body of the 

 insects which visit the flowers, and thus efiect 

 the transportation of the pollen to the stigmas of other 

 flowers. Such flowers are further characterized by the 

 possession of a large, showy perianth, or of odor, or by 

 the secretion of nectar; or they may furnish all these 

 attractions combined. 



73. Of the special adaptations in hermaphrodite flowers, 

 to insure cross-fertilization, dichogamy (Gr. diehoa, asun- 

 der ; gamos, union) is an important one; it means that the 

 stamens and pistil of the same flower do not come to matu- 

 rity at the same time, hence self-fertilization is impossible. 

 The flower is proterandrous (Gr. protos, first; andres, 

 stamens) when the anther ripens and discharges the pollen 



Fig. 131. Plumose stigma of a grass-flower {_roa ^rt^fensis). 



