320 PLANT-LIFE 



of its lure and special devices, this flower seldom obtains 

 a response to its invitation, and because guests do not 

 arrive, fruit is not ripened. Yet the plant obviates 

 failure by a curious device. It sends out vegetative 

 runners, which root at intervals, and in due time bear 

 inconspicuous flowers that never open. Each of these 

 flowers contain two stamens and a pistil. The stamens 

 yield a very small quantity of pollen, and it is sufficient 

 for the fertilization of the ovules in the ovary. Cross- 

 fertilization having failed the plant, it secures the ripen- 

 ing of seed by the production of these self -pollinating 

 flowers, and, so far as we know, there is no detriment 

 thereby to the species. 



The pollination of the Common Ling, or Heather 

 {Calluna vulgaris, Plate LXIIL), is worthy of remark. 

 When its flowers first open they are freely visited by 

 insects, which in sipping honey become dusted with 

 pollen; this they carry to the stigmas of other flowers. 

 At this period there is no possibility of other than insect 

 pollination. But later, when nectar is exhausted, the 

 insects are not attracted. Then the filaments of the 

 stamens elongate, pushing the anthers outwards from 

 the corolla, so that they may be exposed to the wind. 

 The wind is now used as a pollinating agent, carrying the 

 pollen to the stigmas of younger flowers. Thus, the 

 Heather makes assurance doubly sure; it supplements 

 entomophilly with anemophilly. The Toothwort 

 (Plate LIII.) adopts a similar practice. 



The subject of the fertilization of Orchids has been 

 rendered classic by the work of Charles Darwin, to whose 

 volume in relation thereto the reader is referred for a 

 full discussion. An indication of the highly specialized 



