72 THE BOOK OF NATURE STUDY 



shedding, at another in a pollen-receiving stage. The more 

 common state of things is for the stamens to mature and shed 

 their pollen before the stigma is receptive. The flowers of the 

 Rose Bay Willow Herb (Vol. IV.p.i7) and of the Dandelion (Vol. III. 

 p. 147) may be cited as examples of this, but many more of the 

 examples described exhibit it to a greater or less degree. The 

 development of the stigma first, so that it has ceased to be receptive 

 when the flower sheds its pollen, is beautifully shown in the Field 

 Woodrush (Vol. III. p. 153) and the Ribwort Plantain (Vol. III. 

 p. 208). The flowers in which the pollen-shedding and pollen- 

 receiving stages overlap are numerous, and these partially prevent 

 self-pollination and favour cross-pollination. 



The construction of the flower has reference to other things 

 besides the actual pollination. One of these is the protection 

 of the pollen from injury by wet. The mechanism of pollination 

 may not be reconcilable with this, and the risk of wetting is then 

 run, but the Dead-Nettie (Vol. III. p. 141) and many other flowers 

 are examples of thorough protection of the stamens and stigma, 

 in the case of the Dead-Nettie by the upper lip of the corolla. 

 The variety in construction and in method of pollination cannot 

 be fully treated here. We can only look at a few of the general 

 features of wind-pollinated and insect-pollinated flowers. 



In wind-pollinated flowers, of which the Pine, the Ash, the 

 Woodrush, and the Plantains have been described in the preceding 

 pages, we find a number of common features. These flowers lack 

 the bright colouring, the conspicuous petals, and the provision of 

 nectar which are all so important in insect-pollinated flowers. 

 They also show a number of common characters which fit them 

 for wind-pollination. The pollen is loose and powdery, and 

 readily falls from the anthers, and the latter usually project clear 

 of the flower to facilitate this. The stigma also, in the Angiosperms 

 named, is large and prominent, and usually is rough and hairy 

 to offer a good chance of catching the grains of pollen drifting by in 

 the air. Such flowers may be said to economise in the develop- 

 ment of petals and in the secretion of nectar, but have to form a large 

 amount of pollen, since much is wasted, never coming near a stigma. 



Insect-pollinated flowers exhibit much greater variety, and 

 reference must be made to the descriptions of particular examples. 



