Costus root

Costus root

　　Costus root is a perennial herbaceous plant, growing to a height of 1.5–2 meters, with a thick main root. The stems are sparsely covered with short soft hairs. The stem leaves have long petioles, with blades that are triangular-ovate or long triangular in shape, measuring 30–100 cm in length and 15–30 cm in width. The base is heart-shaped, extending downward into irregularly split wing-like structures. The margins are irregularly undulate or shallowly lobed and have sparse prickles, with short hairs on both surfaces; the base of the stem leaves is winged and clasps the stem. The inflorescence is terminal and axillary, with flower heads about 3 cm in diameter, often several gathered at the top of the flower stalk. There are approximately 10 layers of bracts; the corolla is dark purple and five-lobed; there are five stamens with fused anthers; the ovary is inferior, with the style protruding beyond the corolla. The achene is long and conical, with two layers of pinnate pappus at the apex. Flowering occurs from July to August, and fruiting from August to October.