Xixing, also known as Xiaoxin and Xicao, is the whole herb of the plant Asarum heterotropoides, Asarum sieboldii, or Asarum chinense, which belong to the Aristolochiaceae family. Xixing has a warm nature and a spicy taste. It enters the lung and kidney meridians and has the effects of dispelling wind, dispersing cold, promoting diuresis, and opening the orifices. It is used to treat symptoms such as wind-cold headache, nasal congestion, toothache, phlegm-liquid coughing, and rheumatic pain. It should be noted that there is a plant called Asarum heterotropoides var. mandshuricum, which belongs to the Polygonaceae family, that is sometimes falsely labeled as Xixing. Pay attention to distinguish between the two when using.
Genuine Xixing
1. Asarum heterotropoides: It has 1 to 2 leaves, connected to the lower rhizome and roots. Sometimes flowers or fruits can be seen. The leaf stalk is long and has longitudinal veins. The leaf blade is often wrinkled or damaged, thin in texture, gray-green in color, and sometimes with a hint of yellow. It is brittle and easily broken. The flower is solitary, dark purple-brown, and bowl-shaped. The rhizome is irregularly cylindrical, often curled into a cluster, with short branches, 1 to 4 centimeters long and 2 to 4 millimeters in diameter. The surface is gray-brown, rough, with ring-shaped nodes, and the internodes are 2 to 3 millimeters long. The top of the branches has bowl-shaped stem scars. The roots are slender, densely covered with nodes, gray-brown on the surface, smooth or longitudinally wrinkled, with adventitious roots and adventitious root scars at the lower end. It is brittle and easily broken, with a flat, yellow-white cross-section. It has a strong aromatic smell and a spicy taste when chewed, followed by a numb and burning sensation.
2. Asarum chinense: It has a similar appearance to Asarum heterotropoides, but the rhizome is longer, about 3 to 8 centimeters, with very short internodes, only 1 millimeter long. The smell is weaker, and the spicy taste when chewed is also weaker, but the numb and burning sensation is stronger.
False Asarum heterotropoides var. mandshuricum
Also known as Maoguo Jincai, it is a perennial herb. When dried, it shrinks into a cluster. It has numerous basal leaves with narrow wings on the leaf stalks and hairs. The bracts are lanceolate and fused with the leaf stalk at the base. The leaf blades are nearly circular or broadly circular, with a heart-shaped or shallow heart-shaped base. The rhizome is thick and nodulated, with multiple roots, pale brown in color. The flowers are pale purple or nearly white, and the bracts are located in the middle or upper part of the peduncle. The capsule is spherical, about 8 millimeters long, densely covered with white long soft hairs. The pedicel usually bends downward, making the fruit in contact with the ground. It usually splits into three triangular parts, containing numerous ovoid white seeds. It has a weak smell, without the aromatic fragrance of genuine Xixing, and a mild taste without a numbing sensation on the tongue.
Modern pharmacological studies have shown that water or alcohol extracts of Xixing have good anesthesia effects. When used in combination with other Chinese herbs, it can be applied as an anesthetic during tooth extraction, achieving good results. The volatile oil it contains has antipyretic and analgesic effects. It has inhibitory effects on Streptococcus hemolyticus, Shigella, and Salmonella. As for Asarum heterotropoides var. mandshuricum, although it can be used as a medicinal plant, its effects are to clear heat and detoxify, cool blood, and reduce swelling, and it does not have the aforementioned effects of genuine Xixing. Moreover, the two are not plants of the same family, so the false plant cannot be used as a substitute for genuine Xixing.
