CHAPTER LI. 



SEED DISTRIBUTION. 



672. Means for dissemination of seeds. — During late summer or autumn 

 a walk in the woods or afield often convinces us of the perfection and variety 

 of means with which plants are provided for the dissemination of their 

 seeds, especially when we discover that several hundred seeds or fruits of 

 different plants are stealing a ride at our expense and annoyance. The hooks 

 and barbs on various seed-pods catch into the hairs of passing animals and 

 the seeds ma)' thus be transported "^feffi 

 considerable distances. Among the 

 plants familiar to us, which have such 

 contrivances for unlawfully gaining 

 transportation, are the beggar-ticks 

 or stick titrhts, or sometimes called 



Fig. 469. 

 Bur of bidens or bur-marigold, show- 

 ing barbed seeds. 



Fig. 470. 

 Seed pod of tick-treefoil (desmodium) ; atthe 

 right some of the hooks greatly magnified. 



bur-marigold (bidens), the tick-treefoil (desmodium), or cockle -bur (xanfhi- 

 um), and burdock (arctium). 



673. Other plants like some of the sedges, etc., living on the margins of 

 streams and of lakes, have seeds which are provided with floats. The wind 

 or the flowing of the water transports them often to distant points. 



368 



