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A TEXT-BOOK OF BOTANY. 



Rheum officinale is the source of the " South China " rhubarb 

 from Szechwan, Kanzu, and Shensi. The plant is a perennial herb 

 resembling the garden rhubarb. The rhizome is vertical and 

 gives rise to a leafy branch terminated by the inflorescence, which 

 is a panicle. The leaves are large, with a sub-cylindrical petiole, 







FIG. 288. Wild Ginger (Asarum canadense). A, showing habit of plant, consisting of 

 underground root-stock, the kidney-shaped leaves on long petioles, and the short peduncled, 

 bell-shaped flower which develops close to the ground; B, longitudinal section of flower, 

 and C, a transverse section of flower. Bicknell, in Bulletin Torrey Bot. Club, Nov., 1897. 



a cordate or orbicular lamina which is either entire or coarsely 

 and irregularly dentate. There are several nearly related species 

 which also yield the drug. Rheum pal mat u in of Northern China 

 has leaves which are lobed or deeply incised, which character is 

 especially -marked in the variety tanguticum. Rheum Rhaponti- 

 c it in, which yields English rhubarb, has leaves which are heart- 



