Powder
(1) clusters, abundant, 21~155(~190μm)
in diameter; pyramids, obtuse.
(2) starch granules, single or compound.
(3) bordered-pitted, reticulate, spiral
2
and annular vessels, 11~140μm in
diameter.
3 1P
R.palmatum(upper picture): the figure of clusters is
subcycloidal ， the petals of cluster are more，edges and corners are mostly short and small without symmetry ； compound starch granules are consisted by 2~7 branch granules.
vascular bundles. (3) pith broad,
usually showing abnormal vascular bundles scattered (4) parenchymatous cells containing abundant calcium oxalate rosettes (druses or clusters).
木质部 形成层
bundles scattered
韧皮部
(4) parenchymatous 异型V. cells containing
abundant calcium
髓
oxalate rosettes
(druses or clusters).
【Microscopic Identification】
掌叶大黄 Rheum palmatum
药用大黄 Rheum officinale 唐古特大黄 Rheum tanguticum
唐古特大黄
Differences among Rhubarbs

species color
Rheum palmatum
yellowishbrown
Rheum Tanguticum
TLC (thin layer chromatography)
Results: Examine under ultra-violet light, the five
orange fluorescent spots in the chromatogram obtained with the test solution correspond in position and color to the spots in the chromatogram obtained with the reference drug solution
晶形类圆形，晶瓣多，棱角大多短小， 不对称；淀粉复粒由2~7分粒组成。
R. officinale(lower picture): the figure of clusters is
subcycloidal, the edges and corners are mostly broad and symmetrical; compound starch granules are consisted by 2~9 branch granules.
掌状浅裂
Rheum officinale
palmatilobat leaf; flower, yellow.
【Habitat】
Rheum palmatum: Gansu, Qinghai, Tibet, etc. mainly cultivated, 70～80% in commodity Rheum tanguticum: Qinghai, Gansu, Tibet. mainly wild, 5～10% in commodity Rheum officinale: Sichuan, Guizhou, Yunnan; wild and cultivated, 20～30% in commodity
Respective Characters of the Plants in Rhubarb Rheum palmatum: palmatifid leaf; flower, purple
掌状半裂叶
R. tanguticum: palmately parted leaf (partition); flower, purple 掌状深裂 R. officinale: palmatilobate leaf; flower, yellow
rhizome of ① Rheum palmatum 掌叶大黄 as North Rhubarb ② Rheum tanguticum 唐古特大黄 ③ Rheum officinale 药用大黄 ---- as South Rhubarb
【Plant Description】
Common Characters of Polygonaceae: ① having ocreae (stipular sheath) ② simple-perianth flower ③ stamen 6-9
1.69～2.31
free (%)
0.14～0.75
0.30～1.20
1.24～1.31
【Physical-chemical Identification】
Micro-sublimation: the yellow needles or the feather-shaped crystals. Fluorescence Test Test for Combined Anthraquinones TLC (thin layer chromatography)
大黄 Dahuang (Rhubarb)
Radix et Rhizoma Rhei
【Other Names】Jinwen、Chuanjun、Xining Rhubarb、 South Rhubarb、North Rhubarb、General。
【Record】First in the “Shen Nong's Herbal Classic”. 【Source】(Fam. Polygonaceae). the dried root and
reddishbrown
Rheum Officinale
yellowish- or
reddish-brown
texture heavy, close heavy, close light, loose
【Mi. Identification】
1. Tr.S. of Rhizome : (1) most cork removed (2) ectophloic
chrysophanol, aloe of the free anthraquinones
emodin, physicion, etc. (sennoside A、B、C、D)
antibacterial effect
the diarrhetic constituents
free anthraquinones and combined anthraquinones
Constituents Comparison
species
Rheum palmatum
Rheum tanguticum
Rheum officinale
anthraquinone (%)
1.01～5.19
1.14～4.36
3.00～3.37
combined (%)
0.87～4.44
0.82～3.16
晶形类圆形，棱角大多宽而对称; 淀粉 复粒由2~9分粒组成。
【Constituents】
Anthraquinone derivatives
free anthraquinones combined anthraquinones
rhein, emodin,
glucosides or dianthrones
大黄 (Rhubarb)
Radix et Rhizoma Rhei
大黄 Dahuang (Rhubarb)
Radix et Rhizoma Rhei
Source Plant Morphology Habitat Macroscopic Identification Microscopic Identification Constituents Physicochemical Identification Annotation Questions Reference Literatures
extracted with ether again
ether layer+NaOH red color (official rhubarb)
TLC (thin layer chromatography)
Test solution: powder (0.1g)＋MeOH(20ml) 60' (macerate) filtrate to dry ＋H2O(10ml) ＋ HCl(1ml) 30'Δ (water-bath) cool extracted with 20ml of ether (2 times) ether dry ＋CHCl3(1ml). Reference drug solution: Radix et Rhizoma Rhei reference with the same methods . Reference solution: Rhein, emodin, chrysophanol, aloe emodin, physicion ＋MeOH the solution containing 1 mg/ml. Plate: silica gel H. Mobile phase: petroleum ether ( 30-60℃)-ethyl formateformic acid (石油醚-甲酸乙酯-甲酸) (15:5:1) 。