Xian Cao

Mesona chinensis Benth. (Lamiaceae), known as Xian Cao or Liang Fen Cao (grass jelly plant), is an annual herbaceous mint relative native to southern China, Taiwan, and Southeast Asia, where it is widely cultivated for both culinary jelly and medicinal use. Plants are 15-100 cm tall, with quadrangular hairy stems often tinged purple, decumbent at the base and erect above. The opposite leaves are ovate to lanceolate, 2-5 cm long, with coarsely serrate margins, an acute tip, and a pubescent dark green surface that becomes blackish on drying. Small bilabiate flowers, white to pale pink with a purple upper lip, are borne in dense terminal one-sided racemes 2-10 cm long during late summer and autumn, subtended by ovate bracts. The fruit consists of four small smooth nutlets. The dried whole herb, when boiled with starch, releases a polysaccharide gel that sets into the well-known black grass jelly; medicinally it clears summer heat, relieves thirst, cools blood, and supports treatment of mild hypertension and diabetes.