✵The TCM herbalism is also known as pharmaceutics of Traditional Chinese Medicine, or Chinese pharmaceutics, is the branch of health science dealing with the preparation, dispensing, and proper utilization of Chinese herbs. It is majorly composed of Introduction of Chinese Medicinals, Classification of Chinese Herbs, Formulas, and Patent medicines.
Classifications of Herbs:Purgatives Herbs.
Introduction: Purgatives herbs: an agent or substance herbs that promotes defecation or even causes diarrhea, not only for relieving constipation, but also for driving stagnant matter, excessive heat and retained fluid out of the body.
✵Till the date Oct 10th,2019, there are totally  kinds of common TCM herbs,  kinds of related plant species,  kinds of related insect species, are recorded in this category. These purgatives herbs are briefly introduced separately:
Radix et Rhizoma Rhei(Rhubarb).
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, arrest 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.
✵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 of the Polygonales suborder. These 3 commonly used species are introduced as:
(1).Rheum palmatum L.: The Rheum palmatum L., is a plant of the Polygonaceae family and Rheum genus, it is commonly known as "Palmar leaf Rheum", or "Zhǎng Yè Dà Huánɡ"(literally it means Palm leaves Rheum), perennial, up to 2 meters high. Roots and rhizomes are stout, hypertrophic, slightly woody, dark brown on the outside, dark yellow in section, and arranged closely around the cross-section of rhizomes. Stems are erect, stout, glabrous.
Basal leaves and lower leaves with stout long petiole; leaf blade broadly ovate or suborbicular, ca. 35 cm, palmately lobed to semi-fit, base shallowly cordate, lobes are narrowly triangular, apex acute, both sparsely small nipples and short white bristles; cauline leaves are smaller. Inflorescences are conical, terminal, 10~20 cm long. Flowers are small, reddish-purple, several clustered; 6 tepals, arranged in 2 turns; 9 stamens, slightly exposed perianth; nutlet is oblong-elliptic, ca. 10 mm, width 7~8 mm, with 3 prisms, winged along the edge, tip dimpled, base is subcordate, brown. Its flowering period is in June, fruiting from July to August.
Ecological environment: The Rheum palmatum L., grows in the forest, valley wetland, hillside, grassland of 1,500~4,400 meters above sea level, in the alpine mountains, soil moist grass slope, cultivated in north China. Geographical distribution: This species mainly distributes in northwest, west, and southwest areas of China.
The Rheum palmatum L., prefers a cool and humid climate, resistant to cold, avoid high temperatures. Usually it is planted at an altitude of 1,400 meters above sea level, the frost-free period of 120 to 150 days. The underground part can pass winter safely and begin to germinate when temperature reaches at 5 Deg C. The suitable temperature for growth is 15~22 Deg C. Roots are deeper and should be planted in loose, fertile sandy loam. Sticky, low-lying water planting easy roots.
(2).Rheum tanguticum Maxim. ex Balf.: The Rheum tanguticum Maxim. ex Balf., is a plant of the Polygonaceae family and Rheum genus, it is commonly known as "Chicken toe Rheum", or "Táng Gū Tè Dà Huánɡ", or "Jī Zhǎo Dà Huánɡ"(literally it means chicken toe Rheum), tall herb, 1.5~2 meters tall, with thick roots and rhizomes, yellow. Stems are coarse, hollow, striate, smooth, glabrous or with coarse short hairs at upper nodes.
Stem leaves are large, leaf blade suborbicular or broadly ovate, 30~60 cm long, apically narrow and long acute, base slightly heart-shaped, usually palmately 5-parted, base-pair simple lobes, the lobes are mostly three-pinnatifid. The small lobes are long, narrowly lanceolate, with five basal veins. The masks on the leaves are papillary or rough, and the lower ones are short and dense. The petioles are nearly cylindrical and nearly equal in length to the leaves. Rough short hairs; cauline leaves are smaller, petiole is shorter, more lobes more narrow; stipules are large, more broken later, the outer mask covered with rough short hair.
Large panicles, branches tightly clustered, flowers are small, reddish pale red; pedicels filiform, 2~3 mm long, joints located at lower part; tepals are nearly elliptic, inner wheel is larger, ca. 1.5 mm; Most of the stamens are 9 and are not exposed; the disk is thin and connected to the base of the filaments to form a very shallow disk; the ovary is broadly ovate, with a short style, flat extension, and stigma head shape. The fruit is round-oval to oblong, round or truncated at its tip and slightly heart-shaped at its base. It is 8~9.5 mm long, 7~7.5 mm wide, 2~2.5 mm wide, and the edge of the longitudinal veins close to the wings. Seeds are ovate, dark brown. Its flowering period is in June, fruiting period is from July to August.
Ecological environment: The Rheum tanguticum Maxim. ex Balf., grows in an alpine valley at 1,600~3,000 meters above sea level, under the mountain shrubbery or forest margin more damp place. Geographical distribution: This species mainly distributes in the north-west and west areas of China.
The Rheum tanguticum Maxim. ex Balf., prefer cool, dry, and 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 year or 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.: The Rheum officinale Baill., is a plant of the Polygonaceae family and Rheum genus, it is commonly known as "Rheum officinale", or "Dà Huánɡ", perennial herb, stems are erect, 2 meters high, hollow, smooth and glabrous. Basal leaves are large, long and stout fleshy, ca. as long as leaves; leaf blade broadly cordate or suborbicular, ca. 40 cm in diameter, 3~7 deeply palmately lobed, often divided again on each lobe. Small papillae, pilose below; cauline leaves are smaller, shortly stipitate; stipules sheathed, densely pubescent. Inflorescence is large cone-shaped, terminal; pedicel is slender, related to the lower middle section. Flowers are purplish-red or reddish-purple; 6 tepals, ca. 1.5 mm, in 2 turns; 9 stamens; 3 styles. Achenes have 3 edges, wings ribbed, dimples slightly apex, base nearly cordate, dark brown. Its flowering period is from June to July, fruiting from July to August.
Ecological environment: The Rheum tanguticum Maxim. ex Balf., grows in mountain forest edge or grass slope, prefer damp environment, on mountains and grassy slopes and where the soil is thick and sunny, wild or cultivated. Geographical distribution: This species mainly distributes in the southwest, the middle reaches area of the Yangtze River, the middle reaches area of the Yellow River, the area of the Hanjiang River, and other areas of China.
Trait identification:The herb is cylindrical, conical, oval or irregular, 3~17 cm long and 3~10 cm in diameter. In addition to the skin of the surface yellow-brown to red-brown, some visible white mesh texture and star points (abnormal vascular bundle) scattered, residual skin is tan, with many rope holes, and coarse wrinkles. Quality is solid, some center is slightly soft, the cross-section is reddish-brown or yellow-brown, show granular; Rhizome medulla part is broad, have star dot annulus row or scattered; Root is well-developed, with radial texture, cambium ring obvious, no stars. Smell fragrant, taste bitter and slightly astringent, chewing sticky teeth, a sense of sand.