Naturalisation in Extra-Tropical Countries. 459 



Rheum officinale, Baillon.* 



Western China and Eastern Thibet on the high table-land. 

 Height of stem sometimes to 10 feet ; circumference of foliage 

 reaching 30 feet ; blade of leaf 2 feet long and broad [Balfour]. It 

 furnishes most of the true Turkey-Rhubarb, not merely from the root 

 but also from the woody stem. Suited for mountainous regions. 

 Recommended also as a scenic plant by Regel. Hardy still at 

 Christiania. 



Rheum palmatum, Linne.* 



From insular to alpine North-Eastern Asia. Attains a height of 

 9 feet. A variety from the Tangut-country of Mongolia or North- 

 Thibet, found by Col. Przevalski, yields an excellent medicinal root, 

 known as the Kiakhta- or Khansu-Rhubarb [Maximowicz] indeed 

 the best Russian Rhubarb. Cultivation of this variety in Germany 

 on sandy moor-ground developed in the root to a large extent the 

 chrysophanic acid and emodin [Prof. Beilstein]. The plant is 

 valuable also for decorative effect. For medicinal culture alpine 

 valleys with soil rich in lime are needed [Sir Rob. Christison]. 

 For indications of the literature on medicinal rhubarbs see among 

 lexicographic works particularly B. D. Jackson's "Vegetable techno- 

 logy," London Index- Society, 1882. 



Rheum Rhaponticum, Linne. 



From the Volga to Central Asia. This species, together with R. 

 Tataricum, L. fil., R. undulatum, L., and a few others, all Asiatic 

 (one extending to Japan), provide in their acidulous leaf-stalks and 

 unexpanded flower-mass for culinary purposes the ordinary Rhubarb, 

 also known as " Rhapontic." Rhubarb-leaves can also be used in 

 the manner of spinage. In tropical climes this culinary vegetable is 

 available only during the cool season. Propagation generally by 

 division of root. The soil for rhubarb-plants, intended to yield 

 kitchen-vegetable, must be deep and rich. R. spiciforme (Royle) is 

 another edible species, ascending the drier parts of the Himalaya to 

 16,000 feet [Sir Jos. Hooker and Dr. G-. Watt]. 



Rheum Ribes, Gronovius. 



Palestine, Persia, Beloochistan, from 3,000 feet upwards, on wet 

 clay-soil. The native inhabitants are very fond of the young, 

 flowering shoots as food. Foliage scarlet in autumn [Dr. J. 



Aitchison]. 



Rhododendron maximum, Linn. 



North-Eastern America. Attains a height of about 20 feet. 



Irrespective of its being a fine acquisition for any garden-copses,. 



this bush seems of industrial importance, because Mr. C. Forster 

 ft asserts, that the wood of this and the allied Kalmia latifolia, L., is- 



