THE ANGIOSPERMAE 



1517 



Fig. 1387. — Stro- 

 phonthtis speciosus. 

 Apocynaceae. Fruit 

 dehiscing to release 

 seeds with very long 

 plumes. 



Fig. 1386. — Epilobitim niontantim. Long capsules 

 splitting open to release the plumed seeds. 



cynaceae and the Asclepiadaceae, especially 

 the latter, in which the plumes reach their 

 most impressive development, being some- 

 times several inches long (Fig. 1387). One 

 genus, Calotropis, is widely cultivated in the 

 tropics for these seed plumes, which are 

 used for stuffing pillows, and Asclepias ciiras- 

 savka, much cultivated for its flowers, has 

 also naturalized itself widely by its plumed 

 seeds. 



The plumes are generally from one end of the seed and may be reckoned 

 as arils, but in TiUandsia (Bromeliaceae), a genus of epiphytes in tropical 

 America, the plumes are produced from the long straight funicles. The 

 surface of the funicle and the testa develops parallel ribs of elongated, 

 thickened cells, and these ribs eventually separate ofl^, as long " hairs," 

 which remain attached only at the base of the funicle to form a long plume. 



Woolly seeds are not to be distinguished from plumed seeds, except 

 that the hairs grow as a rule all over the testa. The Salicaceae, Salix and 

 Populus, are well known for the woolly fluff in which the seeds are borne. 

 On a windy day the fluff may be seen streaming away on the leeward side 

 of a Willow tree in extraordinary quantity. It is produced even by un- 

 fertilized ovules and, at least in Populus, is therefore frequently seedless, 

 the trees being unisexual. The other important family here is the Mal- 

 vaceae in which four important genera have large capsules full of small, 



