Description from Flora of China
Gymnocline Cassini; Pontia Bubani; Pyrethrum Zinn.
Herbs, perennial, subshrubs, or shrubs, lower parts somewhat woody; indumentum absent or of basifixed and/or medifixed hairs. Leaves alternate, rarely rosulate, pinnatifid to 3-pinnatisect, rarely entire. Synflorescences cymose, mostly flat-topped, sometimes reduced to a solitary capitulum. Capitula heterogamous or homogamous, radiate, disciform or discoid. Involucres campanulate; phyllaries in 3-5 rows, scarious margins broad or narrow, usually brown, less often white. Receptacle convex or flat, epaleate, usually pilose. Marginal florets in 1, very rarely 2, rows, or absent, female, fertile; lamina white or red, less often yellow, or absent, ovate, elliptic, or linear. Disk florets many, yellow, bisexual; corolla tubular, apex 5-lobed. Anther bases obtuse; apical appendage ovate-lanceolate or broadly lanceolate. Style branches linear, apex truncate. Achenes terete or obscurely 3-angled, 5-10(-12)-ribbed, often with sessile glands, never with myxogenic cells. Corona present, 0.1-0.4 mm, sometimes of free scales, rarely an adaxial auricle (very rarely absent).
Tanacetum partheniifolium (Willdenow) Schultz Bipontinus (Tanaceteen, 56. 1844; Pyrethrum partheniifolium Willdenow, Sp. Pl. 3: 2156. 1803, "parthenifolium"; 伞房匹菊 san fang pi ju), native to C and SW Asia, and T. parthenium (Linnaeus) Schultz Bipontinus (Tanaceteen, 55. 1844; Matricaria parthenium Linnaeus, Sp. Pl. 2: 890. 1753; 短舌匹菊 duan she pi ju), originating within Europe, possibly through selection from T. partheniifolium, are cultivated as ornamentals in China and are included in the following key. Tanacetum parthenium is used medicinally.
A gathering by Karelin and Kirilov from Xinjiang ("Sinkiang: Songaria-Kirghisici"), not seen by the present authors, has been named as Pyrethrum achilleifolium M. Bieberstein (Fl. Taur.-Caucas. 2: 327. 1808; Tanacetum achilleifolium (M. Bieberstein) Schultz Bipontinus, Tanaceteen, 47. 1844), a C Asian species recorded west of the W Altai. It would key out below as T. santolina, from which it differs by its phyllaries broader, pubescent only at their bases, and with broader membranous margins.
About 100 species: N Africa, C Asia, Europe; 19 species (two endemic, two introduced) in China.
(Authors: Shi Zhu (石铸 Shih Chu); Christopher J. Humphries, Michael G. Gilbert)