4. Crepidiastrum denticulatum (Houttuyn) Pak & Kawano, Mem. Fac. Sci. Kyoto Univ., Ser. Biol. 15: 56. 1992.
黄瓜假还阳参 huang gua jia huan yang shen
Herbs 30-120 cm tall, annual or biennial. Root vertical, with many fibrous rootlets. Stem solitary, erect, branched predominantly in upper half, glabrous. Leaves glabrous. Basal and lower stem leaves mostly withered in fruit, ± petiolate or sessile, usually oblanceolate, undivided or pinnately divided. Middle stem leaves sessile, base conspicuously auriculately clasping, auricles usually rounded; blade (including auricles) oblanceolate, obovate, pandurate, or ± elliptic, undivided, or pinnatifid or pinnatipartite, margin entire or dentate, apex rounded, acute, or acuminate. Upper stem leaves similar to middle stem leaves but smaller, usually less incised, less dentate, or entire. Synflorescences terminating main stem and branches, corymbiform or paniculiform, with few to many capitula. Capitula with 12-20 florets; peduncle capillaceous. Involucre narrowly cylindric, 6-9 mm. Phyllaries abaxially glabrous; outer phyllaries few, ovate, less than 0.5 mm, apex acute; inner phyllaries ca. (7 or)8, midvein subapically plane, crested, or corniculate. Anther tube and style greenish to blackish upon drying. Achene blackish dark brown, narrowly ellipsoid, 2.5-4.5 mm, with 10-15 apically scabrid ribs, apex attenuate into a beak 1/5-1/3 as long as achene. Pappus white, 3-5.5 mm.
Forests, forest margins, grasslands, dry slopes, among boulders, cliffs, field margins, roadsides; below 100-2000 m. Anhui, Chongqing, Fujian, Guangdong, Guangxi, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Shandong, Shanxi, Sichuan, Yunnan, Zhejiang [Japan, Korea, Mongolia, E Russia, Vietnam].
Based on the treatment by Stebbins (J. Bot. 75: 43-51. 1937) under Ixeris, excluding the misplaced I. denticulata subsp. elegans, I. denticulata subsp. pubescens, and I. denticulata subsp. sonchifolia (see subspecies of Crepidiastrum sonchifolium above), three subspecies are recognized in C. denticulatum. They are not always easily distinguishable and seem linked by transitional populations, but this approach may provide a fairly suitable basis for further, much needed studies.