SPINY FRUITS 263 



5. Another interesting fact comes to light in con- 

 nexion with the kinds of plants that have these 

 winged and hairy seeds and fruits. 



Most of these with winged fruits and seeds are tall 

 trees DOLICANDRONE reaches to 30 or 40 feet, 



MILLINGTONIA to 80 feet, CEDRELA, HOPEA, SHOREA, 



and other DIPTEROCARPEJE are all tall forest trees, 

 others, like PTEROLOBIUM, grow tall as climbers. The 

 much lighter hairy fruits and seeds, of the COM- 

 POSITE, APOCYNACEE and ASCLEPIADACEE belong, 

 on the other hand, to small plants, and moreover to 

 plants which thrive best in the open such as CREPIS, 

 SONCHUS, SENECIO, the Dandelion, Thistle, Valerian, 

 CALOTROPIS and Cotton plant. There are exceptions 

 to this, e.g. WRIGHTIA TINCTORIA with small winged 

 seeds is a small not a large tree, and CRYPTOSTEGIA 

 which has hairy seeds is a tall climber, but for the 

 most part this is the case. On the other hand plants 

 which grow naturally under the shade of other trees, 

 as the wild Balsam, Begonia and Nettle, have plain 

 not winged or hairy seeds. Obviously such appendages 

 would not be of much service in dense woods where 

 the seeds could not in any case be carried far by wind- 



SPINY FRUITS AND SEEDS 



6. There are other fruits which are provided, not 

 with hairs or wings, but with spines or curved 

 or barbed thorns. These readily catch any soft thing 

 that touches them e.g. the hairy covering of mam- 

 mals and in this way the fruit is carried away 

 from the plant. The achenes, for instance, of BIDENS 

 have two barbed bristles just where in others of the 



