Introduction of Long Dan:Chinese Gentian or Radix Gentianae.
✵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:Herbs Clearing Heat and Drying Dampness.
Introduction: Herbs Clearing Heat and Drying Dampness: an agent or substance bitter in taste and cold in property that is effective for eliminating heat and dampness, usually used in the treatment of diseases caused by damp-heat, such as acute jaundice, acute dysentery, urinary infection, eczema, boils and abscesses.
✵Till the date Oct 10th,2019, there are totally  kinds of common TCM herbs,  kinds of related plant species, are recorded in this category. These Herbs Clearing Heat and Drying Dampness are briefly introduced separately:
Radix Gentianae(Chinese Gentian).
Pin Yin Name: Lónɡ Dǎn.
English Name: Chinese Gentian.
Latin Name: Radix Gentianae.
Property and flavor: cold, bitter.
Brief introduction: The Herb Radix Gentianae is the dried root and rhizome of Gentiana manshurica Kitag., Gentiana scabra Bge., Gentiana triflora Pall., or Gentiana rigescens Franch.(Gentiana Tourn.L. genus, family Gentianaceae.), used to clear heat, dry dampness, and purge the liver and gallbladder fire for the treatment of (1).damp-heat in the liver and gallbladder with morbid leukorrhea, jaundice, or eczema, and (2).liver fire with headache, hypochondriac pain, deafness or convulsions. The herb is commonly known as Radix Gentianae, Chinese Gentian, Lónɡ Dǎn.
Gentiana is a perennial herb indigenous to the alpine and sub-alpine pastures of central and Southern Europe. Ringed and forked, the thick wrinkled root is brown on the outside and yellow on the inside. The simple, erect, glabrous stem grows to a height of 120 cm, giving off opposite bluish-green elliptical leaves with prominent curved veins. Three to ten yellow flowers arise together in the axils of bowl-shaped bracts after the root is about ten years old. The fruit is an oblong, two-valved capsule.
Flower and Fruit: The flowers are yellow, terminal, pedicled, and axillary in cyme-like false whorls. The calyx is deeply divided into 2. The corolla is rotated and divided almost to the base into 5 or 6 lanceolate tips. There are 5 stamens with 8 mm long anthers and 1 superior ovary. The fruit is 6 cm long and capsule-shaped. The numerous seed is flat, oblong or round, with a membranous edge.
Leaves, Stems, and Root: Yellow Gentian is a completely glabrous perennial plant that grows to 140 cm high. The rhizome has many heads, and the top of the rhizome can attain the thickness of an arm. The main root is taproot, which grows up to 1 meter long. The stem is round, unbranched, hollow, and grooved in the upper region to finger thickness. The leaves are elliptical, bluish-green, have strongly curved ribs and grow up to 30 cm long and 15 cm wide.
Botanical source: The herb Radix Gentianae (Chinese Gentian) is the dried root and rhizome of species (1).Gentiana manshurica Kitag., (2).Gentiana scabra Bge., (3).Gentiana triflora Pall., or (4).Gentiana rigescens Franch., they are plants of the Gentiana genus, the Gentianaceae family of the Gentianales order. These 4 commonly used species are introduced as:
(1).Gentiana manshurica Kitag.: Botanical description: It is commonly known as "Tiao Ye Long Dan", or row-shape leaf Gentiana. This species differs from Gentiana scabra Bge in that its leaves are thick, subleathery, sessile, upper leaves linear-lanceolate to linear, base obtuse, margin slightly curvaceous. 1 or 2 Flowers; Calyx lobes linear-lanceolate, longer than or as long as calyx tube; Corolla lobes apex acuminate.
Ecological environment: The shrub grows in riverbank, Gobi Desert, or hillside thicket at an altitude of 300~800 meters above sea level. It distributes in the northwest, mainly in the western end of the Qinling mountains to western Gansu, eastern Qinghai, and Xinjiang of China.
Growth characteristics: The Gentiana manshurica prefers to cool climate, soil requirements are not strict, but light clay and anti-humus soil is appropriate. It should not be cultivated in high dryness and strong direct sunlight.
Characters of herbs: the rhizome of gentian is usually straight, tuberous or elongated, 0.5~1.5 cm, 4~7 mm in diameter, 2-16 tufted roots below, often less than 10. Root length is about 15 cm, diameter 2~4 mm; The surface is yellowish-brown or gray-brown, with twisted longitudinal wrinkles, upper fine horizontal lines are obvious, and a few protruding root marks.
Pharmacological actions: The herb contains gentiamarin, and it has a liver protection effect, lower the glutamicpyruvic transaminase, choleretic effect, it also has anti-inflammatory, inhibiting and killing plasmodium. Its component erythricine has a sedative effect, relaxes muscles, and lowers blood pressure. Take a small amount of gentian herb, which can enhance gastric juice secretion, promote digestion. Besides, the herb has diuretic, antibacterial, and anthelmintic action.
Medicinal efficacy: Clearing heat and drying dampness, purging the liver of pathogenic fire and calm the frightened or convulsion. It is indicated for damp-heat jaundice, drenching pain when urinating, swelling itching of genital region, dampness heat and morbid leukorrhea, head swelling and headache due to excessive fire of the liver and gallbladder, red eyes swollen and painful, deafness and swelling of the ear, hypochondriac pain and bitterness in mouth(bitter taste), pyrexia, infantile convulsions and spasm, etc.
Administration of Radix Gentianae(Lónɡ Dǎn):
Administration Guide of Radix Gentianae(Lónɡ Dǎn)
Internally:3~6 grams(CP),Internally:water decoction, 1~3 qian(about 3~9 grams), or prepare to pill,powder.Externally:grinded into powder,mashed and apply stick(DCTM),Internally:water decoction, 3~6 grams, prepared to pill, powder.Externally:proper amount, wash with water decoction, or grinded into powder and smear.(CHMM).
(2).Gentiana scabra Bge.: Botanical description: It is commonly known as Long Dan or Gentiana. Perennial herb, 30~60 cm tall. Rhizome short, tufted with most slender roots, up to 30 cm long. Flower stems solitary, unbranched. Leaves opposite; Sessile; Lower leaves scaly, base united, 5~10 mm long, middle and upper leaves nearly leathery, leaf blade ovate or ovate-lanceolate, 2.5~7 cm long, 0.7~3 cm wide, apex acute or long acuminate, base cordate or rounded, surface dark green, underside pale, margin curvaceous, scabrous; Leaves 3~5 veins. Flowers numerous, fasciculate branchlets and leaf axils, without pedicels; Subinflorescence with 2 lanceolate or linear bracts, 2~2.5 cm long; Calyx campanulate, 2.5~3 cm long, apex 5-lobed, often outwardly reversed or spreading, irregular; Corolla tubular-campanulate, blue-purple, 4~5.5 cm long, sometimes throat with most yellow-green spots, corolla apex 5-lobed, lobes ovate, pleated triangular; 5 stamens, inserted in middle of tube, filaments wide at base; Ovary narrowly elliptic or oblong, 1~1.4 cm long, ovary stalk 1 cm long, style short, stigma 2-lobed. Capsule, oblong, sessile. Seeds numerous, brown, glossy, reticulate, with broad wings at both ends. Its flowering period is from August to September, fruiting from September to October.
Ecological environment: The plant grows in the hillside grassland, roadside, river bank thicket, and undergrowth meadow at an altitude of 200~1,700 meters above sea level. It distributes in the north, the lower reaches area of the Yangtze River, the Zhujiang river area, and other areas, northwest area and other areas of China.
Characters of herbs: rhizome more horizontal, long 0.5~3 cm, 3~8 mm in diameter, with multiple stem marks, more than 4~3 roots, often more than 20 roots, slender cylindrical roots, slightly twisted, 1~3 mm in diameter; Surface hoary or palm yellow color, upper horizontal grain is more obvious, lower part has longitudinal furrow and fine root mark. Brittle, easy to absorb moisture soft, cross-section yellow-brown, yellow-white wood point shape, ring row, central pulp department obvious. Slight smell, very bitter taste.
(3).Gentiana triflora Pall.: Botanical description: It is commonly known as "San Hua Long Dan", or Triple-Flower Gentiana, Gentiana Trifolium. This species differs from the first two species in that the upper and middle leaves are nearly leathery, linear-lanceolate to linear-linear, base rounded. 3 flowers, rarely 5; Calyx lobes narrowly triangular, shorter than calyx tube; Corolla lobes apex obtuse.
Ecological environment: The plant grows in grasslands, glades, and thickets at an altitude of 440~950 meters above sea level. It distributes in the north area of China.
Characters of herbs: the rhizome of Gentiana Trifolium is mostly straight, 1~5 cm long, 0.5 cm in diameter. 7~1.5 cm, more than 4~30 roots, often more than 15 roots, root diameter is 1~6 mm; The surface is yellow and white. All horizontal lines are more obvious.
(4).Gentiana rigescens Franch.: Botanical description: It is commonly known as "Dian Long Dan", Gentiana yunnanensis. Its different features from the first three are: rosette free, cauline leaves multiple pairs, type ii, lower leaves 2-4 pairs, scaly, middle-upper leaf blade ovate-oblong, obovate or ovate, base cuneate, margin slightly curvaceous. Flowers numerous, fasciculate branchlets apically capitate, sparse axillary, surrounded by uppermost bract-like leaf clusters; Calyx lobes irregular, 2 large, obovate-oblong, base narrowly compressed into claws; Stamen inserted on the lower part of the coronal tube. The seeds are yellowish-brown.
Ecological environment: The plant grows in thickets, undergrowth, and valleys of hillside grassland at an elevation of 1,100~3,000 meters above sea level. It distributes in the west of the Zhujiang river area, southwest area of China.
Characters of herbs: the rhizome of gentiana yunnanensis is nodular, with 1~10 residual stems and 4~30 roots. The roots are spindly, slightly curved, with a diameter of 1~4 mm. The surface is light brown or tan; There is white wood core in the middle of the cross-section.
1.Introduction of Long Dan:Chinese Gentian or Radix Gentianae.
2.TCM Books:DCTM(Dictionary of the Chinese Traditional Medicine),CHMM(Chinese Herbal Materia Medica).