Identification and Varieties of Mutong: A Traditional Chinese Medicine

Mutong is a commonly used traditional Chinese medicine. Due to different sources, it contains different chemical components, and its functions and toxicity also vary. Therefore, it needs to be carefully identified. The most widely used species is Guanmutong, followed by Chuanmutong. In addition, there are also Mutong, San Yemutong, or Baimutong in some areas.

I. Identification of the original plants:

1. Mutong: The vine stems of Mutong, San Yemutong, or Baimutong, all of which belong to the Mutong family, are authentic Mutong. These three are all deciduous woody twining vines, ranging from 3 to 15 meters in length.

(1) Mutong: Mainly produced in East China. Palmate compound leaves with 5 leaflets, oblong or elliptic, 3 to 6 cm long.

(2) San Yemutong: Mainly produced in Zhejiang and other places. Trifoliate compound leaves with oval or elongated leaflets, which vary greatly in length and width, with shallowly serrated and wavy edges.

(3) Baimutong: Mainly produced in Sichuan and other places. A variant form of San Yemutong, but the leaflets are entire and thicker in texture.

II. Identification of medicinal materials and prepared slices:

1. Mutong: The stems of the medicinal material are cylindrical and twisted, with a gray or brown surface. The bark is easy to peel off from the wood. The wood is grayish-white or yellowish-white. The vascular pores on the cross-section are dense and irregularly arranged, with a large circular medulla in the center. The prepared slices are irregular thin slices, with a light brown or yellow-brown surface, longitudinal stripes on the periphery, and a gray-green or gray-brown color. They have a slight odor and a bitter taste.

2. Guanmutong: The stems of the medicinal material are elongated cylindrical, with a diameter of 1 to 6 cm. The surface is grayish-yellow or light brownish-yellow, with shallow longitudinal grooves and patchy brown cork remnants. The texture is light and hard. The cross-section is yellowish-white or yellow, with a narrow bark and a wider wood. The vascular pores are mostly needle-like or arranged in multiple concentric circles, interspersed with white ray-like structures resembling a spider web. The medulla is small and narrow. The prepared slices are circular thin slices, with a wide wood and multiple layers arranged in a ring-like pattern, with radial patterns and small holes, and a thin bark. The texture is light and hard. It has a slight odor and a bitter taste.

3. Chuanmutong: The stems of the medicinal material are cylindrical with fine longitudinal grooves and ridges on the surface. The outer skin has longitudinal fissures. The nodes are swollen, and the cross-section has radial patterns and vascular pores. The medulla is yellowish-white or yellow-green and has voids. The prepared slices are circular thin slices, with a pale yellow or yellow color, radial patterns and cracks on the surface, and small holes all over, with a small white medulla, occasional cavities, and a brownish-yellow periphery with longitudinal grooves and ridges. The texture is hard, odorless, and has a mild taste.