213 



N. Ord. POLYGONACEJE. 



Tribe Eliabarbarea. 



Genus Rheum,* Linn. Meisner, in DC. Prod., xiv, pp. 3237. 

 Species 20 or more, natives of Northern Asia, China, 

 Persia, and the Himalayas. 



213. Rheum officinale, Baillon in Adansonia, x, p. 246 (1872). 

 Thibetan Rhubarb. 



Figures. Hep. de 1'Association Francaise, 1872, t. 10, reprod. in Adan- 

 sonia, xi, tt. 8, 9; Bot. Mag., t. 6135 (Dec., 1874); Neues Eepert. fur 

 Pharmacie, xxv (1876). 



Description. A large, perennial, herbaceous or semi-fruticose 

 plant, possessing after the first two or three years of its life (accord- 

 ing to Baillon) 'a very thick aerial stem persisting through the winter, 

 with branches about 10 16 inches long, as thick as a man's thigh, 

 suddenly tapering to a blunt apex and covered externally with a 

 dark brown coat formed of the dried and withered, closely-placed 

 leaf -bases and ocreas of former years, many of which have leaf- 

 buds in their axils, internally fleshy or semi-pulpy, with a yellowish 

 or orange-coloured juice ; the lower part of the stem giving off 

 large, thick, adventitious roots. Lower leaves very large, closely 

 placed, alternate, on very long petioles, stipulate, spreading on 

 all sides, at first reddish; petioles about 18 inches long, widely 

 dilated at the base, nearly cylindrical above, about 1| inch thick, 

 solid, perfectly glabrous or pubescent with very short white hairs, 

 longitudinally striate, bright green ; stipules (ocrese) very large, 

 membranous, at first obovoid, entire, afterwards orange-brown and 

 torn ; blade from 2 4^ feet long, and somewhat more wide, sub- 

 orbicular, palm ately- veined, with 5 7 nearly equal, shallow lobes, 

 base cordate or reniform, margin irregularly and coarsely cut, 

 veins thick, very prominent beneath, much reticulated, upper 

 surface smooth, pale clear green, under surface paler, covered with 

 a fine white pubescence ; upper leaves few, distant on the 



* Rheum, in Greek pfjov or pa, was the name of the drug in classical times. 



