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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 pahnatum of Northern China 

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

 especially marked in the variety tanguticum. Rheum Rhaponti- 

 cum, which yields English rhubarb, has leaves which are heart- 



