REPORT ON THE BOTANY OF THE ATLANTIC ISLANDS. 15 



most striking example. Absence of winged fruits, as Composites, which form so great an 

 element in the North American flora, is remarkable. 



A constitutional property exhibited by the only two common woody plants of arboreous 

 habit, the cedar and the palmetto, deserves mentioning, as it accounts for their being able to 

 maintain their preponderance against all comers. It is an extraordinary power of repro- 

 duction from seed, rendered certain by the protection of the seed itself — in the one case by 

 an indurated testa, and in the other by an exceedingly dense endosperm. Seed is borne in 

 great abundance and of a high degree of fertility by both ; and ground that is left uncul- 

 tivated is speedily clothed with seedlings of the cedar. 



The whole question of the origin of insular floras will be more fully discussed in the 

 general introduction to the Botanical Reports of the Challenger Expedition. 



