78 STICKY SEEDS. [chap. 



the wretched animal tries to tear them out. and some 

 times getting them into his mouth perishes miserably. 



The cases in which the diffusion of fruits and seeds 

 is effected by their being sticky are less numerous, and 

 we have no well-marked instance among our native 

 plants. The common Plumbago of South Europe is 

 a case which many of you no doubt have observed. 

 Other genera with the same mode of dispersion are 

 Pittosporum, Pisonia, Boerhavia, Siegesbeckia, Grin- 

 delia, Drymaria, &c. There are comparatively few 

 cases in which the same plant uses more than one of 

 these modes of promoting the dispersion of its seeds, 

 still there are some such instances. Thus in the 

 common Burdock the seeds have a pappus, while the 

 whole flower-head is provided with hooks which 

 readily attach themselves to any passing animal. 

 Asterothrix, as Hildebrand has pointed out, has three 

 provisions for dispersion ; it has a hollow appendage, 

 a pappus, and a rough surface. 



But perhaps it will be said that I have picked out 

 special cases ; that others could have been selected, 

 which would not bear out, or perhaps would even 

 negative, the inferences which have been indicated ; 

 that I have put the cart before the horse ; that the 

 Ash fruit has not a wing in order that it may be 

 carried by the wind, or the Burdock hooks that the 

 heads may be transported by animals, but that 

 happening to have wings and hooks these seeds are 

 thus transported. Now doubtless there are many 

 points connected with seeds which are still un- 

 explained ; in fact it is because this is so that I was 

 anxious to direct attention to the subject. Still I 



