WIND-POLLINATED FLOWERS 421 



It should always be kept in mind that many of the most 

 successful plants, including a large number of troublesome 

 weeds, are capable of self pollination. 



395. Wind-pollinated flowers. 1 It has already been mentioned 

 that some pollen is dry and powdery, and other kinds are more 

 or less sticky. Pollen of the dusty sort is light, and therefore 

 adapted to be blown about by the wind. Any one who has been 

 much in cornfields after the corn has " tasseled " has noticed the 

 pale yellow/ dusty pollen which flies about when a cornstalk is 

 jostled, and which collects in considerable quantities on the 

 blades of the leaves. Corn is monoecious, but fertilization is 

 best accomplished by pollen blown from the " tassel " (stamens) 

 of one plant being carried to the " silk ' ' (stigma and style of 

 the pistils) of another plant. This is well shown by the fact, 

 familiar to every observing farmer's bov, that solitary cornstalks. 



J O / * i/ 



such as often grow very luxuriantly in an unused barnyard or 



O e/ v v 



similar locality, bear very imperfect ears or none at all. The 



common ragweed is remarkable for the great quantities of 



pollen which shake off on to the shoes or clothes of the 



passer-by, and it is wind-pollinated. So, 



too, are the pines, and these produce so 



much pollen that it has been mistaken 



for showers of sulphur, falling often at 



long distances from the forests where it FIG. 321. Pistil of a grass, 



was produced. The pistil of wind-polli- provided with a feath- 



, , , ery stigma, adapted for 



nated flowers is often leathery and thus wind-pollination 



adapted to catch flying pollen grains 



After Thome 



(Fig. 321). Other characteristics of 



such flowers are the inconspicuous character of their perianth, 



which is usually careen or greenish, the absence of odor and 



i/O O 



of nectar, the regularity of the corolla, and the development 

 of the flowers before the leaves or their occurrence on stalks 

 raised above the leaves. 



1 See Miss Newell, Botany Reader, Part II, Chapter vn. 



