THE FACTORS OF DISTRIBUTION 65 



the seed, as in the Water-lilies (Castalia), in which genus 

 . it is between the aril and the testa, and in the Coco-nut, in 

 which it is between the fibres of the mesocarp ; and 

 (ii.) the power of resisting the action of sea- water. A 

 berry -bearing plant of Asparagus has been observed to 

 float for eighty-five days, and its seeds have withstood 

 immersion in sea-water for more than a year; while 

 t :opical seeds not uncommonly sprout on the north- 

 western coasts of Europe after drifting across the 

 Atlantic.i 



No adaptations can be more unmistakably efficacious 

 "than the waxy epicarp, fibrous air-containing mesocarp, 

 and dense, impervious endocarp of the Coco-nut (Cocos 

 nucifera L.) and such similar plants as the Double 

 Coco-nut of the Seychelles (Lodoicea Sechellarum Labill.) 

 and Nipa fruticans Thunb. The last mentioned, the 

 smallest of the three, is common in the brackish Sunder- 

 bunds, floating for many miles in the waters of the 

 Ganges and the Bay of Bengal without losing the power 

 of germination, as its fossil ally Nipadites seems to have 

 done in the tropical British seas of the Eocene period. 

 Lodo'icea was known as " coco-de-mer " in the Indian 

 Ocean before it had been found growing, while the Coco- 

 nut is almost universal on tropical shores. 



ANEMOCHORES. Extreme lightness, whether of almost 

 ; .the entire plant; of a head of fruits, as in Trifolium 

 xubterraneum L. and allied species, the blue-green grass 

 ^pinifex squarrosus L. on Asiatic shores, and many of 

 he wind-witches of the interior of that continent; or 

 ; single fruits, like those of some of the steppe Umbel- 

 ferce, or the inflated pods of the Bladder Senna (Colutea 

 rborescens L.), is an important adaptation to wind- 

 carriage. Pods of Leguminosce, usually many-seeded, 

 gai lightness in some cases by becoming only one- 

 seeued. 



The very varied structural origin of the many wings 

 and plumes or " parachutes " on fruits and seeds is 

 remarkable, the former being specially characteristic of 

 trees and of plants which by climbing attain to situations 

 exposed to wind. It is also noteworthy that the wings 



1 Thus seeds of Ipomcea grandiflora, a tropical strand-plant 

 collected in 1888, and placed for a year in sea-water, germinated 

 at Kew in 1891; and seeds of Entada did so after floating from 

 the West Indies to the Azores, a distance of 3000 miles. 



E 



