What kind of herb is Tongcao? The latest answer is here
Tongcao is the stem pith of the Araliaceae plant Tetrapanax papyrifer, also known as Koutuo, Linan, Huoduo, Yishang, Tongtuomu, Congcao, Baitongcao, etc. It is distributed in Jiangsu, Hubei, Sichuan, Guizhou, Yunnan and other places. At present, the Chinese market mostly uses Chuanmutong, Baimutong and Tetrapanax papyrifer as substitutes, while Japan uses Akebia quinata and Akebia trifoliata, and the Taiwan, China market mostly uses Chuanmutong and Akebia longiracemosa. The mainland once used Guanmutong as a substitute, but it was banned because it is toxic.
The stem of Tongcao is slender, cylindrical and twining. The stem bark is grayish brown, with round, small raised lenticels. The bud scales are arranged in an imbricate manner and are light reddish brown. The palmately compound leaves are alternate or clustered on short branches, usually with 5 leaflets, and the petioles are slender. The leaflets are papery, obovate or obovate-elliptic, with a rounded or concave apex and a small mucro, and a rounded or broadly cuneate base. The upper surface is dark green, and the lower surface is pale bluish white. The midrib is sunken above and raised below. The petiolules are slender, 8-10 mm long, and the middle one can reach 18 mm.
The corymbose racemes of Tongcao are axillary, with 1-2 female flowers at the base and 4-10 male flowers above them. The peduncle is 2-5 cm long, borne on shortened lateral branches, and its base is enclosed by bud scales. The flowers are slightly fragrant. The pedicels of male flowers are slender, while those of female flowers are slender and long, with 6-9 staminodes. The fruit is paired or solitary, oblong or elliptic, purple when mature, and dehiscent along the ventral suture. The seeds are numerous, ovate-oblong, and the seed coat is brown or black and glossy. The flowering period is April to May, and the fruiting period is June to August.
Tongcao likes light and warmth, and grows well in moist, fertile soil. Its roots have strong lateral growth ability and can form a large number of root suckers. It is not very cold-tolerant, and the overwintering temperature should be above 5°C. It is suitable for cultivation in fertile sandy loam and often grows in grass under forests on low-altitude slopes. It grows well in slightly acidic yellow soil rich in humus, and can also adapt to neutral soil. The stems and vines often grow prostrate on the ground. It is produced in Jiangsu, Hubei, Sichuan, Guizhou, Yunnan and other places.
Tongcao is propagated by sowing, cuttings or root cuttings in early spring. Seeds are used for seedling raising in early spring. The underground stems have very strong sprouting ability. In winter, part of the underground stems is dug and injured to stimulate new seedlings to grow in the second year. By the third year, before germination in early spring, these new seedlings are transplanted and planted at a row spacing and plant spacing of 1.3 m each. In autumn and winter, the base is cut, the head and tail and young branches are removed, the rough outer bark of the woody column is scraped off, and it is sun-dried. During drying, the vine stems are straightened, and when they are 70% to 80% dry, they are graded by diameter and tied into bundles, then further dried.
According to different processing methods, Tongcao is divided into Tongcao and cinnabar-processed Tongcao. After processing, it is stored in a dry container, placed in a ventilated and dry place, and protected from moisture. Tongcao is sweet and bland in taste and slightly cold in nature, entering the lung and stomach meridians. It has the effects of clearing heat, promoting diuresis, and promoting lactation. It mainly treats damp-heat strangury, edema with scanty urine, insufficient lactation and other conditions, but it should be used with caution by those with deficiency of both qi and yin, middle-jiao cold, no internal damp-heat, and pregnant women.