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FOC | Family List | FOC Vol. 20-21 | Asteraceae | Sinosenecio

23. Sinosenecio oldhamianus (Maximowicz) B. Nordenstam, Opera Bot. 44: 50. 1978.

蒲儿根 pu er gen

Senecio oldhamianus Maximowicz, Bull. Acad. Imp. Sci. Saint-Pétersbourg 16: 219. 1871; S. martini Vaniot; S. savatieri Franchet; Sinosenecio savatieri (Franchet) B. Nordenstam.

Herbs, annual or biennial, rhizomatous, with leafy stems. Stems solitary or few, erect, 40-80 cm or taller, sparsely villous and arachnoid, glabrescent to subglabrous. Radical leaves withered by anthesis, long petiolate; lower stem leaf petioles 3-6 cm, white arachnoid, basally somewhat expanded; blade adaxially green, ovate-orbicular or suborbicular, 3-5(-8) × 3-6 cm, membranous, abaxially white arachnoid, sometimes ± glabrescent, adaxially sparsely arachnoid or subglabrous, palmately 5-veined, base cordate, margin shallowly to deeply duplicate-dentate or duplicate-serrate with mucronulate teeth, apex obtuse to acute, acuminate and mucronulate. Upper leaves shortly petiolate, smaller, with ovate or ovate-deltoid, basally cuneate blades; uppermost leaves ovate or ovate-lanceolate. Capitula numerous, arranged in compound terminal corymbs; peduncles 1.5-3 cm, slender, sparsely pubescent, usually with a basal linear bract. Involucres broadly campanulate, 3-4 × 2.5-4 mm, not calyculate; phyllaries ca. 13, oblong-lanceolate, ca. 1 mm wide, herbaceous, with membranous margins, white arachnoid or puberulent to glabrous, apically acuminate and sometimes purplish. Ray florets ca. 13; corolla tube 2-2.5 mm, glabrous; lamina yellow, oblong, 8-9 × 1-2 mm, 4-veined, apically 3-denticulate, obtuse. Disk florets numerous; corolla yellow, 3-3.5 mm, with 1.5-1.8 mm tube and campanulate limb; lobes ovate-oblong, ca. 1 mm, apically acute. Anthers oblong, 0.8-0.9 mm, basally obtuse, appendages ovate-oblong. Style branches recurved. Achenes cylindric, ca. 1.5 mm, smooth and glabrous in ray florets, puberulent and papillate in disk florets. Pappus absent in ray florets, in disk florets white, 3-3.5 mm. Fl. Jan-Dec. 2n = 26*.

Forest margins, streamsides, wet rocky and grassy places, margins of cultivated fields; 400-2100 m. Anhui, Chongqing, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shanxi, Sichuan, Yunnan, Zhejiang [Myanmar, Thailand, Vietnam].

Sinosenecio oldhamianus is a rather derived species in the genus with respect to floral morphology, chromosome number, and habit. Its achenes have differentiated into two types: those in ray florets larger in size, glabrous, and epappose, and those in disk florets smaller, puberulent, and pappose. Its chromosome number is 2n = 26, the lowest in the genus. It is the only annual or biennial species of Sinosenecio and is the commonest and most widespread one to exhibit weedy tendencies.


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