Costus root

Costus root

　　Costus root – Plant morphology: A perennial herb with almost no stem. The root is thick, stout, and cylindrical. Leaves grow in tufts in a rosette pattern, either ovate-lanceolate, oblong-lanceolate, or elliptical, measuring 20–30 cm in length and 10–20 cm in width. They are pinnately mid-slit with 5–7 pairs of lobes, or sometimes entire, with irregularly serrated edges on the lobes; both surfaces are hairy. The petiole is 8–20 cm long. The capitula (flower heads) are several, clustered at the branch tips; the involucral bracts consist of 6 layers, are leathery, green with purple hues, apex acuminate, and edges have cilia. All flowers are tubular, purple, about 4 cm long. The achenes are flattened and ribbed; the pappus is bristly. Flowering period is July to August, fruiting period is August to September.

　　It grows in alpine grasslands at altitudes above 3,000 m. It is mainly produced in Sichuan.

　　Harvesting and processing: Roots are dug up between September and December, cleaned, and then dried in the sun or lightly baked over a low flame.

　　【Characteristics】The root is cylindrical or semi-cylindrical with longitudinal grooves, 10–30 cm in length and 1.5–3 cm in diameter. The surface is yellowish-brown to dark brown, rough, and shows a dense, oblique square mesh pattern formed by fiber bundles. Sometimes the root head is charred black and sticky. The texture is light, hard, and brittle, difficult to break; the fracture surface is uneven, with a yellowish-brown cortex and yellowish-white xylem. Dot-like oil cavities and radial fissures are visible, and some centers may be hollow. It has a distinctive aromatic fragrance, a bitter taste, and becomes sticky when chewed.

　　【Chemical constituents】The rhizome contains volatile oils; commercial costus root contains mokko lactone.

　　【Properties and flavor】Warm in nature, acrid and bitter in flavor.

　　【Functions and indications】Regulates qi and relieves pain, harmonizes the stomach and reduces distension, and checks diarrhea. Used for abdominal distension and borborygmus, poor appetite, abdominal pain, and tenesmus in dysentery.