What is the difference between Solomon's seal (Yuzhu) and Siberian Solomon's seal (Huangjing)? A quick guide to tell the two apart

Yuzhu is the dried rhizome of Polygonatum odoratum, a perennial herb of the genus Polygonatum in the Liliaceae family. It was first recorded in the Shennong Bencao Jing, where it was listed as a top-grade drug under the original name Nülou. The Mingyi Bielu calls it Weirui, and in Hunan it is also called Weishen.

Huangjing was first recorded in the Mingyi Bielu and listed as a top-grade drug. There are many botanical sources; broadly speaking, the commercial drug can be divided into two types: chicken-head Huangjing and ginger-shaped Huangjing. Chicken-head Huangjing is the dried rhizome of Polygonatum sibiricum, a few Polygonatum macropodum, and Polygonatum stenophyllum, all perennial herbs of the genus Polygonatum in the Liliaceae family; ginger-shaped Huangjing is the dried rhizome of Polygonatum kingianum, Polygonatum cyrtonema, and Polygonatum cirrhifolium, all perennial herbs of the genus Polygonatum in the Liliaceae family.

Both of these Chinese medicinal materials are clearly recorded in successive dynasties' materia medica and in the 2000 edition of the Chinese Pharmacopoeia. Their nature and flavour, channel tropism, effects, usage and dosage, and macroscopic identification all differ. However, because the two are plants of the same family and genus and are very closely related, and because their slices look very similar after processing, chicken-head Huangjing from the north and Yuzhu from the north are especially easy to confuse. In order to correctly distinguish the two medicinal materials, their macroscopic identification, nature and flavour with channel tropism, functions and indications, and usage and dosage are introduced separately below:

Macroscopic identification of the medicinal materials

Yuzhu: This product is cylindrical, slightly flattened and somewhat curved, mostly unbranched. It is 5-20 cm long and 0.5-1.2 cm in diameter. The surface is pale yellow or pale yellowish-brown, semi-transparent, with obvious ring-like nodes that are wavy and slightly raised. The texture is hard and brittle, becoming soft when damp, and it breaks easily. The fracture is horny, roughly the same colour as the exterior, and sticky. Commercial goods are considered best when the roots are thick, long and uniform, pale yellow, and horny in the inner fracture. The decoction pieces are irregular, subrounded or oblong thick slices; the cut surface is granular or horny, with scattered off-white vein dots visible, sometimes with a hollow centre, and the periphery has longitudinal wrinkles, with ring-like nodes and round stem scars visible.

Huangjing: The commercial drug is broadly classified into chicken-head Huangjing and ginger-shaped Huangjing.

1. Chicken-head Huangjing: This product is irregularly conical or cylindrical, with one end swollen and often bearing 1 to several short, thick protrusions or small branches, resembling a chicken's head, and with 1-3 stem-base scars that are round-dot shaped, resembling chicken eyes. It is 3-10 cm long, 1-2.5 cm in diameter at the thick end, and 5-8 cm at the thin end. The surface is yellowish-white to yellowish-brown, semi-transparent. The whole body has fine longitudinal wrinkles and relatively obvious wavy ring-like nodes; the fibrous root scars are dot-like protrusions, mostly concentrated on the swollen part. The texture is hard, and when not completely dry it is soft and pliable; the fracture is light brown, with many scattered small yellow vascular bundle dots visible. The odour is slight, the taste slightly sweet, and it is sticky.

2. Ginger-shaped Huangjing: It is irregularly nodular and lumpy, slightly flattened and resembling ginger in shape, 3-10 cm long, 2-4 cm wide, and 1-2 cm thick. The surface is earth-yellow, rough, with irregular wrinkles; the above-ground stem scars are disc-shaped and often sunken. The fibrous root scars are mostly wart-like protrusions, evenly distributed over the whole body. The nodes are obvious, forming raised wavy rings. The rest is the same as chicken-head Huangjing.

The decoction pieces of both types of Huangjing are irregular thick slices of 2-4 mm, with wavy ring-like edges on the periphery. The former has a white to yellowish-brown surface, semi-transparent, with many scattered small vascular bundle dots; the latter has a yellowish-brown, rough surface with irregular wrinkles.

Nature and flavour with channel tropism

Yuzhu: Slightly cold in nature, sweet in taste, entering the Lung and Stomach channels.

Huangjing: Slightly warm in nature, sweet in taste, entering the Lung, Spleen and Kidney channels.

Functions and indications

Yuzhu nourishes yin and moistens dryness, and promotes fluid production and quenches thirst. It is mainly used for damage to Lung and Stomach yin, dry cough due to Lung heat, vexing heat and thirst, dry throat, and similar conditions.

Huangjing has tonic and strengthening effects and antibacterial action. It is mainly used to treat weakness of the Spleen and Stomach, cough due to Lung deficiency, and conditions such as diabetes, hypertension and insufficiency of essence and blood.

Usage and dosage

Yuzhu: Used raw as slices; because its action is mild and weak, the dosage is relatively large. For decoction it is generally 9-15 g, and when used as a cardiotonic tonic the dosage may reach 30-60 g.

Huangjing: Steamed until black-red and then sliced; in the Beijing area it is mixed evenly with yellow rice wine, steamed and sliced. The usual dosage for decoction is 9-30 g. A 2% extract can be used as an external liniment for treating tinea cruris and tinea pedis.