Description from Flora of China
Artemisia annua f. macrocephala Pampanini; A. chamomilla C. Winkler; A. stewartii C. B. Clarke; A. wadei Edgeworth.
Herbs, annual, 70-160(-200) cm tall, much branched, sparsely puberulent, soon glabrous, strongly aromatic. Leaves gland-dotted. Lowermost stem leaves: leaf blade ovate or triangular-ovate, 3-7 × 2-6 cm, 3(or 4)-pinnatipartite; segments 5-8(-10) pairs. Middle stem leaves: petiole 1-2 cm; leaf blade 2(or 3)-pinnatisect or pectinatisect; lobules deeply serrate to pectinate; teeth triangular, 1-2 × ca. 0.5 mm; rachis narrowly winged, sparsely serrate or not; midvein prominent adaxially. Uppermost leaves and leaflike bracts 1(or 2)-pinnatipartite. Synflorescence a panicle to 15 × 8 cm, produced from most nodes to form broad, conical compound panicle. Capitula many, shortly pedunculate, closely subtended by whorl of bracteoles, nodding. Involucre globose, 1.5-2.5 mm in diam.; phyllaries broad and scarious, ± glabrous. Marginal female florets 10-18. Disk florets 10-30, bisexual; corolla dark yellow or yellow. Achenes ellipsoid-ovoid. Fl. and fr. Aug-Oct. 2n = 18.
Artemisia annua contains, among other essential oils, artemisinin (青蒿素 qing hao su). It is well known in Traditional Chinese Medicine for its anti-inflammatory, antifebrile, and hemostatic properties, and artemisinin has become widely valued as an effective treatment for strains of Plasmodium resistant to other anti-malarial drugs.
Hills, waysides, wastelands, outer forest margins, steppes, forest steppes, dry floodlands, terraces, semidesert steppes, rocky slopes, roadsides, saline soils; 2000-3700 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [widely distributed in N Africa, Asia, Europe, and North America].