中亚紫菀木 zhong ya zi wan mu

Aster alyssoides Turczaninow var. achnolepis Handel-Mazzetti.

Subshrubs 20-40 cm; rhizome thick. Stems numerous, erect or ascending, many branched in lower part, finely striate, woody at base, bark reddish brown, gray-white tomentulose, ± glabrescent, upper part herbaceous, gray-white villous, ± glabrescent, glandular distally. Leaves crowded, ascending or erect, linear-oblong to linear, (8-)12-15 × 1.5-2 mm, abaxially densely gray-white villous, adaxially gray-green, moderately to sparsely villous, base attenuate, margin revolute, apex acute. Capitula radiate, 8-10 × ca. 10 mm, in loose corymbiform synflorescences or solitary at ends of branches; peduncles rather thick, straight or curved; bracts small, linear. Involucre broadly campanulate, 6-7 × ca. 9 mm; phyllaries 3- or 4-seriate, imbricate, white villous to arachnoid, glandular at least distally, margin broadly scarious, erose, apex acuminate to acute or ± obtuse, usually purplish red, outer short, ovate or lanceolate, inner oblong. Ray florets 7-13, tube ca. 2.9 mm, glabrous, lamina pale purple to pale lilac, 10-12 × 1.2-2.7 mm; disk florets 11-19(-26), yellow turning reddish, ca. 5 mm, tube 1.8-2.5 mm, tube and limb base sparsely hairy, limb narrowly campanulate to funnelform, ca. 2.7 mm. Achenes straw-colored, 3-3.5 mm, white strigose. Pappus white or pale cinnamon. Fl. and fr. Jul-Sep.

Meadows, gritty-stony foothills, stony riverbeds, open sand dunes, deserts, grasslands; 1300-3400 m. Gansu, Nei Mongol, Ningxia, Qinghai, SE Xinjiang [S Mongolia].

Three varieties have been recognized, but morphological differences appear to be tenuous or the result of phenotypic plasticity. A thorough study is needed before recognition of these varieties is warranted. The varieties are Asterothamnus centraliasiaticus var. centraliasiaticus, A. centraliasiaticus var. procerior Novopokrovsky (Bot. Mater. Gerb. Bot. Inst. Komarova Akad. Nauk S.S.S.R. 13: 340. 1950), and A. centraliasiaticus var. potaninii (Novopokrovsky) Y. Ling & Y. L. Chen (Fl. Reipubl. Popularis Sin. 74: 263. 1985; Asterothamnus potaninii Novopokrovsky, Bot. Mater. Gerb. Bot. Inst. Komarova Akad. Nauk S.S.S.R. 13: 341. 1950, "Potanini"). The main distinguishing characters given in descriptions were number of capitula in synflorescences (loose corymbiform in var. centraliasiaticus vs. 2 or 3 capitula in loose synflorescences in var. procerior and var. potaninii) and the degree of vestiture (gray-white tomentulose and glabrescent in var. centraliasiaticus vs. permanently, densely gray-white tomentose in var. procerior; var. potaninii not mentioned). The typical variety is reported throughout the range of the species; A. centraliasiaticus var. procerior is reported from W Gansu, N Qinghai, and SE Xinjiang; and A. centraliasiaticus var. potaninii is reported from E Gansu and Ningxia.