26 PLANT LIFE. 



air spaces, and which can float in the water, giving out 

 their pollen as they pass down stream. The neat 

 arrangement in the foreign Vallisneria is described in all 

 books on the subject. 



(xii.) In the Common Nettle the stamens are rolled up 

 in a very remarkable manner. When gently loosened, 

 or when heated in the palm of the hand, they 

 suddenly uncoil, and a little cloud of pollen is thrown 

 out. This, therefore, is again another method. The 

 elasticity of the stamen-stalk scatters the pollen, 

 which is then carried by the wind. The Barberry- 

 has a very curious method of opening its anthers. 

 Instead of a slit being formed to allow the pollen 

 to escape, a small piece at the top is nearly cut off 

 in an oblique manner, forming a sort of valve or cap. 

 The stamen-stalks, or filaments, have a sensitive spot 

 near their base. When an insect's foot touches this, 

 the stalk of the stamen springs up; and, owing to the 

 peculiar valve-like opening of the anther, a shower of 

 pollen covers the insect. 



Among the other important points connected with 

 flowers, it must be remembered that they require pro- 

 tection {a) against rainy weather, which would destroy 

 the pollen, (/;) against cold, during which no insects are 

 at work, and the pollen would be wasted, {c) against 

 strong sunlight, which might injure the tissues, especially 

 when young, and {d) they must also be guarded against 

 such creatures as the Apple-sucker, Apple-weevil, etc. 

 (see p. 93). 



Now the drooping flowers of the Hyacinth, Lily of the 

 Valley, Heathers, Bluebells and Harebells are clearly a 

 very neat and efficient protection against the rain. In 

 almost all the Dead-nettle order, the two upper petals 

 are brought forward as a little roof, neatly covering the 



