What kind of plant exactly is Tu Fuling (Smilax glabra)?
Tu Fuling, also known as Bai Yuliang, Ci Zhuling, Guo Shanlong, Leng Fantuan, etc., is the dried rhizome of the lily family plant Smilax glabra. Smilax glabra mostly grows on hillsides or under forests, and is distributed in Anhui, Zhejiang, Jiangxi, Fujian, Hunan, Hubei, Guangdong, Guangxi, Sichuan, Yunnan and other places in China. Only its dried rhizome is selected for medicinal use, and it has the effects of detoxifying, removing dampness, and benefiting the joints.
Tu Fuling is a climbing shrub, 1-4 mm long. The stem is smooth and thornless. The rhizome is thick and blocky, often connected by stolons, 2-5 cm thick. The leaves are alternate, the petiole 5-15 mm long, accounting for about 3/5-1/4 of the total length, with a narrow sheath, often having 2 slender tendrils, with the abscission point near the apex. The leaf blade is thinly leathery, narrowly elliptic-lanceolate to narrowly ovate-lanceolate, 6-12 cm long and 1-4 cm wide, with an acuminate apex and a rounded or obtuse base, usually light green underneath.
The umbel of Tu Fuling is solitary in the leaf axil, usually with more than 10 flowers. The peduncle of the male inflorescence is 2-5 mm long, usually noticeably shorter than the petiole, rarely nearly equal to the petiole in length, with 1 bud between the peduncle and the petiole. The peduncle of the female inflorescence is about 1 cm long. The female flowers resemble the male flowers in appearance, but the inner tepals have no teeth at the margin and have 3 staminodes. The berry is 6-8 mm in diameter, black when ripe, with a bloom. The flowering period is from May to November, and the fruiting period is from November to April of the following year.
The dried rhizome of Tu Fuling is irregularly blocky, slightly flattened-cylindrical and curved rather than straight, mostly branched, with nodular swellings, about 5-15 cm long and about 2-5 cm in diameter. The surface is earthy brown or brown, rough, often with knife cuts and residual parts of lateral roots, and with stem scars at the upper end. The texture is hard, not easy to break, the fracture is rough, powdery, and light brown. The odor is slight, and the taste is sweet and bland.
Tu Fuling slices are long thin slices, varying in size, about 1-3 mm thick, with irregular edges, light brown or light yellow, and a smooth or slightly rough surface. There are slightly visible vascular bundle dots in the middle, and on careful observation a gravel-like luster can be seen, and longitudinal slices commonly show grain. The vessels are irregular, rich in powder, slightly elastic, and after moistening with water, they feel smooth to the touch. Those that are light brown, sufficiently powdery, and low in fiber are considered better.