288 GEOGRAPHICAL DISTRIBUTION OF PLANTS. 



Terebinthace^e, or Anacardiace^e. — Rhus radicans or 

 toxicodendron, the poison oak ; R. aromatica, the fragrant 

 sumach ; and R. glabra, the smooth sumach, reach the banks 

 of the Saskatchewan, or latitude 45°. R. typhina and R. ve- 

 nenata extend to Canada, but have not been discovered north 

 of Lake Superior. 



LEGUMXNOSiE. — Amorpha fruticosa, false indigo ; A. cane- 

 scens, lead plant ; and A. nana, grow abundantly on the 

 prairies of Osnaboya, and are the only shrubby leguminous 

 plants which extend to Rupert's Land. Robinia pseudacacia 

 is plentiful in Canada East. 



CjESALPINEjE. — Gymnocladus canadensis, the Kentucky 

 coffee-bean tree ; Cercis canadensis, red bud ; and Cassia 

 chamacrista, partridge pea, have their northern limits in 

 Canada or Wisconsin. 



Rosacea. — Prunus americana,the wild yellow plum, seems to 

 reach its northern boundary on the River Winipeg, not having 

 been observed by me beyond the 50th parallel. Lieut. Abert 

 gathered its fruit as far south as the banks of the Canadian and 

 Pawnee forks of the Arkansas, on the 40th parallel. It is a 

 common bush on the river banks in the Northern States. The 

 American plums and cherries require further investigation, as 

 the number of the species and their distinctive characters are 

 imperfectly known. This one grows to the height of ten or 

 fifteen feet on the Winipeg, producing in the woods long flexible 

 branches, armed with a few slender sharp thorns. Its ripe fruit 

 is fleshy and well flavoured, but rather mealy, of a yellowish 

 colour inclining to orange. It has an ovoid shape, with a 

 shallow groove on one side like a peach, is nearly an inch in 

 diameter, and its stone is so much compressed that its thickness 

 is less than half its width ; while its length, being 0*63 inch, 

 exceeds the width by a fourth part. The nut is oblique, with 

 convex valves, being circumscribed by two unequal curves. 

 One edge is acute, with a groove on each side of it ; the other 

 edge is occupied by a narrow groove. I have been thus par- 

 ticular in the description of the northern fruit, that it may be 

 compared with plums growing in other districts. The fruit is 



