Introduction of Da Huang:Rhubarb or Radix et Rhizoma Rhei.

TCM Herbalism:Medicinals and Classifications. ✵The article gives records of the herb Rhubarb, its English name, Latin name, property and flavor, its botanical source three plant species, ①.Rheum palmatum L, ②.Rheum tanguticum Maxim. ex Balf, ③.Rheum officinale Baill., with a detailed introduction to the botanical features of these three plants, the growth characteristics, and ecological environment of these three plants, the features of the herb Rhubarb, its pharmacological actions, medicinal efficacy, and administration guide.

Radix et Rhizoma Rhei(Rhubarb).

deep yellow root slices of Radix et Rhizoma Rhei are piled together Pin Yin Name: Dà Huánɡ.
 English Name: Rhubarb.
 Latin Name: Radix et Rhizoma Rhei.
 Property and flavor: cold nature, tastes bitter.

 Brief introduction: The herb Radix et Rhizoma Rhei is the dried root and rhizome of Rheum palmatum L., Rheum tanguticum Maxim.ex Balf., or Rheum officinale Baill., used to induce catharsis, clear heat, purge fire, stop bleeding, counteract toxins and remove blood stasis, for treating (1).constipation with gastrointestinal accumulation, (2).warm diseases with high fever, delirium, and constipation, (3).postpartum abdominal pain, amenorrhea due to blood stasis, (4).hemoptysis, hematemesis and epistaxis associated with excessive heat in the blood, and, externally, (5).for burns, boils, and sores. The herb is commonly known as Radix et Rhizoma Rhei, Rhubarb, Dà Huánɡ.

 Botanical source: Common herbal classics and other famous herbal classics defined the herb Rhubarb Root(Da Huang) as the dry root and rhizome of the plant species (1). Rheum palmatum L, (2). Rheum tanguticum Maxim. ex Balf, or (3). Rheum officinale Baill. They are plant species of the Rheum L. genus, the Polygonaceae family (smartweed or buckwheat family) of the Polygonales suborder. These 3 commonly used species are introduced:

(1).Rheum palmatum L.


 a flowering plant of Rheum palmatum L with red flower spike grow in grass land Botanical description: The plant, Rheum palmatum L is a plant of the Polygonaceae family (smartweed or buckwheat family) and Rheum genus, it is commonly known as Palmar leaf Rheum, or Zhǎng Yè Dà Huánɡ (means Palm leaves Rheum). A perennial tall herb, stems are upright, the plant grows up to about 2 meters high, hollow, smooth, and glabrous. Roots and rhizomes are stout (thick and strong), hypertrophic, and slightly ligneous (woody), out bark is dark brown, the cross-section is dark yellow, and arranged closely around the cross-section of rhizomes.

 a flowering plant of Rheum palmatum L with a red flower and some big green leaves grow in woods Basal leaves are big, and has stout and long succulent long petiole, about equal length as leaf blade; leaf blades are broadly cordate or orbicular (suborbicular), about 35 cm in diameter, or over 40 cm in diameter, palmately 3-7-parted, each lobe is often pinnately divided again, the upper surface is sparse papillulate, the under surface has pilose; cauline leaves are smaller, has short petioles; ocrea (leaf sheath of stipule) is terete (tubiform), densely pubescent.

 Inflorescences are big conical, apical, 10~20 cm long. Pedicels are thin and long, and have nodes in the middle and lower part. Flowers are small, prunus (violet-red), or purplish, several flowers grow in a cluster; 6 tepals, about 1.5 mm long, arranged in 2 whorls; 9 stamens, slightly stretch beyond perianth;3 styles.

 Achenes have 3 ridges, wings grow along ridges, the front tip is slightly emarginated, and the base is nearly cordate, darkish brown (dust-colour). Its flowering period is from June to July, and the fruiting period is from July to August.

 a colorful drawing of Rheum palmatum L.,brown root,red flower spikes,green leaves Ecological environment: Rheum palmatum grows in mountainous region and forest edges, grassy slopes, valley wetlands, hillsides, grassland, in the alpine mountains, in areas at altitudes of 1,500~4,400 meters above sea level, it is also cultivated in north China. Geographical distribution: This species is mainly distributed in the northwest, west, and southwest areas of China.

 a flowering plant of Rheum palmatum L. with a red flower spike grow in mountain Growth characteristics: The Rheum palmatum L., prefers a cool and cold climate, resistant to cold, and avoids high temperatures. It grows wildly in alpine regions at altitudes of around 2,000 meters above sea level, usually it is planted in regions at altitudes of 1,400 meters above sea level, the lowest temperature in winter is below -10 °C (Celsius, or 14 degrees Fahrenheit), and the temperature in summer is not over 30 °C (Celsius, or 86 degrees Fahrenheit), frost-free period is 150–180 days, yearly precipitation is around 500~1000 mm. Its requirements in soil are strict, generally, it is appropriate to choose fields with deep soil layers, humus-rich loam, or sandy loam with good drainage for cultivation, but it is not appropriate to choose heavy acid soil and low-lying water-logged ground for cultivation. Avoid continuous cropping, plant after 4–5 years.

(2).Rheum tanguticum Maxim. ex Balf.


 plants of Rheum tanguticum Maxim. ex Balf. with many green red leaves grow in field Botanical description: The plant, Rheum tanguticum Maxim. ex Balf is a plant of the Polygonaceae family (smartweed or buckwheat family) and Rheum genus, it is commonly known as Chicken toe Rheum, or Táng Gū Tè Dà Huánɡ, or Jī Zhǎo Dà Huánɡ (means chicken toe Rheum), a tall herb, the plant grows up to 1.5~2 meters tall, roots and rhizomes are stout (thick and strong), yellow. Stems are thick, and hollow, have ridge lines, smooth and glabrous, or have rough short hairs at the nodes of the upper part.

 a colorful drawing of Rheum tanguticum Maxim. ex Balf.,brown root, reddish stem and green leaves,pink flower spikes Cauline leaves are large, leaf blades are orbicular (subrotund) or broadly ovate, 30~60 cm long, the apical end is narrow and long, sharp-pointed, the base is slightly cordate, usually palmately 5-parted, the pair of lobes at the base is simple, the three lobes in the middle are mostly tripinnatipartite. Lobules (lobelets) are narrow and long lanceolate, with five basal veins. The upper surface of leaves is papillary or rough, and the under surface has dense short hairs; the petioles are subcylindrical (nearly cylindrical), and nearly equal length as leaf blades, covered with rough short hairs; cauline leaves are smaller, petioles are shorter too, lobes are more and narrow; ocreae (leaf sheath of stipule) are big type, mostly broken later, have rough short hairs outside.

 Large panicles, branches are tightly clustered, flowers are small, prunus (violet red) and rarely faint red (pale red); pedicels are filamentose (filiform), 2~3 mm long, nodes located at the lower part; tepals (perianth lobes) are nearly elliptic, inner whorl is bigger, about 1.5 mm long; mostly has 9 stamens, and not exposed outside; the floral disc (flower disc) is thin and connected to the base of the filaments, and form a very shallow disk; the ovary is broadly ovate, style is short, explanate, and stigma is capitate.

 The fruit is rectangular-circular oval to rectangular-circular, its tip is round or truncated, its base is slightly cordate, 8~9.5 mm long, 7~7.5 mm wide, wings are 2~2.5 mm wide, and vertical veins are near to the edges of the wings. Seeds are oval (egg-shaped), and dark brown (black brown). Its flowering period is in June, and the fruiting period is from July to August.

 The morphological characteristics of this species are extremely similar to Rheum palmatum L., and the main differences are: leaves are deeply parted, lobes are often triangular-lanceolate or narrowly linear, and lobes are narrow and long. The branches of the inflorescence are close and dense, upright upward, and tightly appressed to the stem.

 a colorful drawing of Rheum tanguticum Maxim. ex Balf.,green leaf,red flower spike Ecological environment: The plant grows in alpine valleys, in areas at altitudes of 1,600~3,000 meters above sea level, under the mountain shrubbery or forest margin, and in damp places. Geographical distribution: This species is mainly distributed in the northwest and west areas of China.

 The plant prefers a cool and dry climate, and is cold-resistant. It is easy to rot with high temperatures and humidity. This species should be planted in deep, well-drained sandy soil. Neutral and slightly alkaline soils are appropriate. The vitality of rhubarb is strong, and the seed germination power can be maintained for 3–4 years. Only the leaf clusters were formed in the second year after sowing. It returns to green in early April and blossoms in May and June in the third year and matures from June to October.

(3).Rheum officinale Baill.


 some plants of Rheum officinale Baill. with red brownish flower spikes grow in field Botanical description: The plant, Rheum officinale Baill is a plant of the Polygonaceae family (smartweed or buckwheat family) and Rheum genus, it is commonly known as Rheum officinale, or Dà Huánɡ. A perennial tall herb, stems are upright, the plant grows up to 1.5-2 meters high, root and rhizomes are stout (thick and strong), and yellow inside. Stems are stout, base is 2-4 cm in diameter, hollow, has fine groove ridges, covered with white short hairs, dense on the upper part and nodes.

 Basal leaves are large; leaf blades are orbicular (subrotund), rarely broadly oval, 30-50 cm in diameter, or length is slightly bigger than width, the apical tip is nearly sharp-pointed, the base is nearly cordate (subcordate), palmately lobed, lobes are big dentate triangular, 5-7 basal veins, the upper surface of leaves is smooth and glabrous, occasionally has sparse short hairs along leaf veins, the under surface has hazel (pale brown) short hairs; petioles are thick cylindrical, equal length as leaf blade or slightly shorter, has ridge lines, covered with short hairs; cauline leaves gradually turn smaller upward, leaf axil on the upper part has inflorescence branch; ocreae (leaf sheath of stipule) are broad and big, length reaches 15 cm, at the initial stage it is amplexicaul (stem-clasping), later cracks, the inner surface is smooth and glabrous, densely pubescent outside.

 Large panicles, branches expand, 4–10 flowers grow in a tuft, green to yellowish white; pedicels are thin and long, 3-3.5 mm long, nodes are in the middle and lower part; 6 tepals (perianth lobes), inner whorl and out whorl are nearly same size, elliptic or slightly narrow elliptic, 2-2.5 mm long, 1.2-1.5 mm wide, edges are slightly orderless; 9 stamens, not exposed;floral disc (flower disc) is thin, valviform; ovary is oval (egg-shaped) or ovoid, style is retroflexed, stigma is sphaerocepharous.

 Fruits are oblong-elliptic, 8-10 mm long, 7-9 mm wide, the tip is rounded, the central part is slightly concave downward, the base is shallowly cordate, wings are about 3 mm wide, vertical veins approach to the edges of wings. Seeds are broad-ovate (broadly ovate). Its flowering period is from May to June, and the fruiting period is from August to September.

 a colorful drawing of Rheum officinale Baill.,brown root,green leaf,and yellow flower spikes Ecological environment: The plant grows in mountainous forest edges or grass slopes, and prefers a damp environment, on mountains and grassy slopes and where the soil is thick and sunny, wild or cultivated. Geographical distribution: This species is mainly distributed in the southwest, the middle reaches of the Yangtze River, the middle reaches of the Yellow River, the area of the Hanjiang River, and other areas of China.

 dried dark yellow herb slices of Rhubarb Root are piled together Characters of herbs: The herb is cylindrical-like, conical, fusiform (spindle-shaped), oval (egg-shaped), or irregular block, 3~17 cm long, and 3~10 cm in diameter. When the bark is removed, the surface is yellow-brown to reddish-brown, off-white reticulated patterns are visible, and scattered star dots (heteromorphous vascular bundles), and for those roots with bark the surface is brown, has cross wrinkles and vertical grooves, the apical tip has a residual base of cauline leaves. The cross-section is mostly uneven and not flat. The texture of the herb is firm and farctate, some are slightly floppy in the center, and uneasily broken, the fracture surface is light reddish-brown or yellowish-brown, and has granularity; The medulla of the rhizome is broad, has stars arranged in circles or scattered; The xylem (wood part) of the root is well-developed, with radial patterns, cambium ring is inconspicuous and has no star dots. The herb has a delicate fragrance, it tastes bitter and slightly puckery, sticky to teeth when chewed, and has a sense of sand.

 Pharmacological actions: ①.purgative effect; ②.inhibit both Gram-positive and Gram-negative bacteria, Staphylococcus aureus, Streptococcus, Diphtheria bacillus, Bacillus subtilis, Bacillus anthracis, Typhoid bacillus, Paratyphoid bacillus, and Dysentery bacillus; ③.inhibit melanoma, breast cancer, and ascites cancer in mice.

 Medicinal efficacy: Inducing purgation and attack accumulation, break stagnation and stasis, clear heat and purging fire, clear dampness and heat, purging pyretic toxicity(toxic heat), purging the pathogenic fire, cooling the blood and detoxification, remove stasis and restoring menstrual flow, activate blood stasis, remove dampness through diuresis and removing jaundice, dispel phlegm, detoxification. It is indicated for excessive heat indigestion and constipation, dyspepsia and distention fullness (food retention, distention fullness), blood heat and hematemesis or epistaxis, hematemesis (spitting blood), epistaxis (nose bleeding or bleeding from five aperture or subcutaneous tissue), red eye (hot eye), swelling and pain in throat, sore of mouth and tongue, emesia of stomach heat (stomach heat and vomiting), swelling ophthalmalgia, abdominalgia with intestinal abscess (abdominal pain, intestinal abscess), blood stasis and menostasis (stagnation of blood and menostasis), postpartum stasis blocking, abdominal mass and lumps, injuries from falls, dampness-heat dysentery,onset of dysentery, rectal tenesmus, jaundice and red urine, stranguria, edema, edema and abdominal fullness, stranguria with turbid discharge, difficulty in urination, delirium (delirious speech, wild talks), seasonal epidemic heat, yang jaundice, erysipelas (inflammatory disease with redness of skin), large carbuncle and pyogenic infections, carbuncle swelling, malignant boil;Externally for scald and burn injury. The wine prepared Rhubarb is good at clearing pyretic toxin in the upper energizer, indicated for red eye and pharyngeal swelling, gingival atrophy. The prepared Rhubarb is smooth in purgation, clearing fire and detoxification, indicated for virulent fire carbuncle ulcer. The charred Rhubarb functions in cooling blood, remove stasis and stanch bleeding, indicated for blood heat stasis and bleeding syndrome, etc.

 Administration of Radix et Rhizoma Rhei (Dà Huánɡ): 
 
Reference: Administration Guide of Radix et Rhizoma Rhei (Dà Huánɡ)
TCM Books: ①.Internally: 3~15 grams, better not decoct long time for the purpose of purgation. Externally:proper amount, prepare to finely ground herb powder, apply stick at affected area; ②.Internally:water decoction, better not decoct long time for the purpose of purgation, 1~4 qian (about 3~12 grams);or prepare to pill, powder. Externally:prepare to finely ground herb powder, mixed with water or vinegar and apply stick at affected area; ③.Internally:water decoction, 3~12 grams, better not decoct long time for the purpose of purgation;or brewing with boiling water and extract juice;prepare to finely ground herb powder,0.5~2 grams;or prepare to pill, powder. Externally:proper amount, prepare to finely ground herb powder, apply stick or wash with water decoction, smear apply.
 Contraindications,Precautions and Adverse Reactions:the herb Radix et Rhizoma Rhei should be used cautiously during pregnancy, menstruation, lactation period, before and after childbirth. The herb should not be combined with Resina Toxicodendri.

 

 
  

 

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References:
  • 1.Introduction of Da Huang:Rhubarb or Radix et Rhizoma Rhei.

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