1512 



RHEUM 



BHfiUM (Rha was the old Greek name for rhubarb). 

 r>!>idonacece. RHUBARB. Twenty species of robust 

 perennial herbs, according to Meisner (DC. Prodr. 14, 

 pp 32-37), natives of Asia and Russia. Lvs. mostly 

 radical very large, entire or divided, on stout, thick 



2097. Rhapis humilis. (See page 1511.) 



petioles: fls. perfect, small, greenish or whitish, pedicel- 

 late, in numerous panicled fascicles or racemes, the in- 

 florescence elevated above the Ivs. on stout, mostly hol- 

 low scape-like stems, which are provided with sheath- 

 ing stipules or ocrese (Fig. 2098) ; the perianth 6-parted 

 and spreading; stamens 9 or 6: ovary 3-angled and 

 bearing 3 styles, ripening into a winged or sometimes 

 nearly succulent akene. 



Aside from the common Rhubarb, Rheum Rhapon- 

 ticum, which is grown for the edible leaf-stalks, the 

 species are little known in general cultivation. Few 

 plants are more useful, however, for bold and striking 

 foliage effects; and these effects are heightened by the 

 towering flower-panicles. Most of the species are hardy 

 and easy to grow, but they profit by a liberal winter 

 mulch. Rheums are usually seen to best advantage 

 against a heavy background of foliage or of rock (Fig. 

 1045, p. 733). Even the common Rhubarb is a useful 

 ornamental subject when well placed. In order to se- 

 cure large and fine foliage, the soil should be rich and 

 moist. The species are propagated by dividing the 

 roots, preferably in spring, leaving as much root as 

 possible with each strong bud. 



The dried rhizomes of Rhubarb are used medicinally. 

 Several species afford the officinal product. It is now 

 believed, however, that the larger part of the dried 

 Rhubarb imported from the Orient is made from the 

 crown or short stem (not the flower-stem) of R. offic- 

 inale. It. Rhaponticum is sometimes grown for its 

 roots. 



A. Foliage undivided, the margins of the Ivs. nearly or 

 quite entire. 



B. Lvs. (at least on the flower stalks) acute or 



acuminate. 



Rhap6nticum, Linn, (i.e., Pontic Rha, "Rhubarb of 

 Pontus,"a province of Asia Minor). RHUBARB. PIE- 

 PLANT (in the U. S.). WINE-PLANT. Fig 2098. Strong 



RHEUM 



perennial, with thick clustered roots: petioles semi- 

 cylindric, plane above: If. -blades suborbicular, deeply 

 cordate at base, undulate, about 5-ribbed, glabrous and 

 shining above, pubescent on the veins beneath : panicles 

 tall and narrow, somewhat leafy, densely flowered, the 

 pedicels jointed below the middle, the fls. whitish: 

 akene oblong-oval. In deserts and subalpine parts of 

 southern Siberia. Nearly everywhere grown in this 

 country for the succulent acid petioles, which are used 

 in early spring for" pies and sauces. Wine is sometimes 

 made from the juice. In France, known usually as an 

 ornamental plant. There are several garden varieties. 

 See Rhubarb. 



undulatum, Linn. Petioles semi-terete, lightly chan- 

 neled above, the leaf-blades ovate-cordate and strongly 

 undulate (basal sinus not so deep as in the last), 5-7- 

 ribbed, glabrous above and puberulent beneath, the 

 upper ones long: panicle narrow and leafy below, the 

 pedicels jointed near the base: akene ovate or oval. 

 Siberia. Small plant, earlier than R. Rhaponticum. 



BB. Lvs. obtuse. 



Emddi, Wall. Stem tall and leafy: petioles semi- 

 terete, somewhat concave above, the margins obtuse: 

 leaf -blades large, ovate, cordate, obtuse, somewhat un- 

 dulate, 5-7-ribbed, the under surface and the margin 

 pubescent: panicles fastigiately branched, the fls. dark 

 purple, pedicels jointed below the middle: akene large, 

 ovate or oblong-oval. Himalaya, in alpine and subal- 

 pine regions. B.M. 3508 (this figure is questioned by 

 Meisner, who thinks it may represent R. australe). 

 Foliage has a coppery hue. 



AA. Foliage, more or less lobed, the margins of the Ivs. 

 or segments usually toothed or notched. 

 B. Lvs. shallowly or obscurely lobed. 

 compactum, Linn. Stem tall: petioles sulcate, plane 

 above: leaf-blades thickish, broad-ovate, cordate, un- 

 dulate and obscurely lobed, very obtuse, glabrous and 

 shining above, the margin strongly toothed, the veins 

 very prominent: panicle with drooping branches: akene 

 large, dark-colored. Siberia to China. 



BB. Lvs. deeply lobed or evenly divided. 

 palniatum, Linn. (R. sanguineum, Hort. ). Stem tall 

 and leafy: petioles subcylindrical, the margin rounded: 

 leaf-blades broad, suborbicular and cordate, 3-5-ribbed, 

 scabrous, deeply paLnately lobed; the lobes ovate-ob- 

 long or lanceolate, acute, entire, dentate or pinnatifid: 

 panicle leafy, with pubescent branches, the pedicels 

 scarcely longer than the fls. : akene oblong-oval and 

 subcordate. Northeastern Asia. 



Var. Tanghuticum, Hort. (R. Tanghuticum, Hort.). 

 Lvs. more elongated and not so deeply lobed. 



hybridum, Murr. Petiole long, 

 canaliculate above and sulcate 

 beneath: leaf-blades ovate, 3-5- 

 ribbed, the base cuneate or 

 scarcely cordate, incise-dentate, 

 puberulent beneath : panicle lax, 

 leafy: akene large, ovate. Seems 

 to be unknown wild. Perhaps a 

 hybrid series between R. palnxi- 

 tum and R. Rhaponticum. Per- 

 haps R. officinale is concerned 

 in it. This name does not occur 

 in the American trade, but it is 

 not unlikely that the plant is in 

 cult, in this country. 



Collinianum, Baill. Probably 

 one of the R. hybridum series, 

 with much-cut broad lobes that 

 extend half the depth of the leaf- 

 blade: fls. red. China. 



officinale, Baill. Figs. 1045, 

 2099. Robust, with a short 

 branching stem or crown 4-10 iu. 

 high : Ivs. very large, 1-3 ft. 

 across, round-oval, more or less 

 pointed or acuminate, hairy, 3-7-lobeti, the lobes extending 

 one-third or one-half the depth of tlie blade npd sharply 

 angled-notched : flower-stems 3-5 ft., much branched, 



2098. Ocrea or stipular 

 sheath of Rhubarb. 



