ALLIACEOUS PLANTS. 291 



bulbs arc planted, and produce ground-onions of a 

 considerable size, while the stem supplies a succession 

 of bulbs for the next year's planting. * 



This variety is said to have been introduced here 

 from Canada ; the French call it Vognon d'Egypte ; 

 there is no proof, however, of its being a native of 

 the country which its name would indicate, while the 

 probability is greatly to the contrary. It is not in 

 such a climate, but in cold ajid wet countries, that 

 seminal plants are changed to viviparous. The same 

 species of grass which has perfect seeds upon warm 

 and dry grounds, bears little plants in the spike when 

 grown upon the cold and humid mountain top ; and 

 the corn, which in a dry season remains firm and 

 without any signs of vegetation in the grain, sprouts 

 in the ear, and becomes green and matted in the 

 shock, when the weather is rainy ; this effect being 

 produced much more frequently in the northern parts 

 of the country than in the south. It is by no means 

 improbable that in the humid atmosphere of the He- 

 brides, both grain and pulse would become viviparous, 

 if they were not taken to the barn and dried by arti- 

 ficial means. By analogy drawn from facts it is 

 therefore probable that the tree-onion is not only from 

 Canada, but that it is not indigenous there, being 

 merely the common onion introduced from France by 

 the colonists, and changed to the viviparous form by 

 the climate. 



The GROUND, or POTATO ONION is another curious 

 variety. This multiplies itself in an opposite direc- 

 tion to that of the tree-onion, producing, by the for- 

 mation of young bulbs on the parent root, an ample 

 crop below the surface. This plant has also been 

 described as being a native of Egypt, or at least as 

 having been brought from that country by the British 

 army in the early part of the present century. It 



* Hort. Trans. , vol. Hi. 



