SOME PLANT MARRIAGES 



461 



instantaneously, the contents flying out like the puff of smoke from a 

 distant gun. 



The only other group of wind-pollinated plants which need be noticed 

 here is that which comprises the forms with immovable flowers. In these 

 it is usual to find that provision is made for temporary storage of the 

 pollen should no ivind be stirring ivhen the anthers dehisce. For instance, 

 in the Arrow-grass (Triglochin pahistre] the pollen is rolled into the deep 

 concavities of the perianth leaves ; while in the Sea-buckthorn (Hippophae 

 rhamnoides) it is discharged into little bladders formed by the uniting 

 concave scales in which the stamens lie. Let a warm dry wind spring 

 up, and the bladders open by narrow chinks, and set free the pollen 

 which, however, can only escape a little at a time. The Broad-leaved 

 Pond-weed (Potamogeton natans) is a good example of a wind-pollinated 

 plant with immovable flowers. 



Here our chapter must close, though not for lack of matter to carry 

 us farther. The subject of the Pollination of Plants is inexhaustible, and 

 must ever remain so; for, in pursuit of the study, we are brought again 

 and again as in the study of the Life of Plants to the borders of the 

 Unknown Land. Here it is that questions press upon us which, as Sahleiden 



Photo by] 



FIQ. 566. HORNBEAM (Carpinua betulus). 



The male flowers are in pendulous catkins two inches in length. The female flowers form a large spike, which 

 lengthens after fertilization to three or four inches, and becomes pendulous. Those shown are the male catkins. 



