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Aster L.
紫菀屬
SOEJIMA, Akiko & PENG, Ching-I
Mostly perennial herbs, subshrubs or shrubs, seldom annual or biennial herbs. Leaves simple, alternate, those of basal rosettes usually dissimilar to cauline leaves, those of peduncle often bract-like, mostly dentate. Heads heterogamous, solitary and terminal or variously corymbosely or paniculately arranged, radiate, rarely discoid. Involucral bracts in 2-6 imbricate, usually graduated series, margins herbaceous. Receptacle naked, often flat or convex, pitted or alveolate. Ray florets pistillate and fertile, in 1 (-2) series, ligules white, pink, blue or purple. Disc florets mostly yellow, all bisexual and fertile, corolla regular, narrowly tubular or funnelform, limb sometimes abruptly dilated at throat, 5-lobed. Anthers obtuse or subauriculate at base, with narrow scarious terminal appendages. Style of ray florets filiform, style of disc florets with flattened branches and linear-lanceolate, acute or acuminate appendages longer than stigmatic area. Achenes oblong-obovoid, mostly somewhat compressed, usually pubescent. Pappus usually in 1 row, similar in ray and disc florets, sometimes very short or absent, or only absent in ray florets, rarely in 2 rows with an outer row of shorter scale-like bristles.
A large, complex genus of more than 600 species, cosmopolitan in distribution. In Taiwan, about 16 species, one of which is represented by two varieties.
KEY TO SPECIES
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1 |
Heads 5-6 mm across. |
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Aster subulatus |
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Heads more than 10 mm across. |
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(2) |
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2 (1) |
Biennial herbs; involucral bracts nearly equal long. |
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(3) |
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Perennial rhizomatous herbs; inner involucral bracts longer than outer except in A. takasagomontanus. |
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(5) |
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3 (2) |
Pappus uniform on ray and disc florets, 5 mm long. |
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Aster altaicus |
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Pappus dimorphic, 1 mm long on ray florets, 5 mm long on disc florets. |
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(4) |
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4 (3) |
Leaves oblanceolate to linear, apex acute or obtuse, hispidulous rarely glabrous. |
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Aster hispidus |
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Leaves elliptic-lanceolate to obovate, apex rounded to obtuse, nearly glabrous. |
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Aster oldhamii |
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5 (2) |
Small alpine plants, 5-20 cm tall. |
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(6) |
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Large plants 50-110 cm tall. |
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(9) |
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6 (5) |
Radical leaves spatulate; involucral bracts nearly equal long; heads 2.5-3.5 cm across. |
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Aster takasagomontanus |
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Radical leaves oblong to lanceolate, petiolate; inner involucral bracts longer than outer; heads less than 2 cm across. |
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(7) |
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7 (6) |
Stems to 5 cm tall. |
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Aster itsunboshi |
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Stems to 20 cm tall. |
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(8) |
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8 (7) |
Leaves oblong, apex acute. |
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Aster chingshuiensis |
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Leaves lanceolate, apex acuminate. |
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Aster morrisonensis |
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9 (5) |
Leaves narrowly ovate to oblong, long petiolate. |
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Aster formosanus |
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Leaves oblong to lanceolate, elliptic, or ovate, sessile or shortly petiolate. |
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(10) |
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10 (9) |
Radical leaves present at anthesis. |
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Aster taoyuenensis |
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Radical leaves withering at anthesis. |
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(11) |
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11 (10) |
Pappus 0.2-0.5 mm long. |
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(12) |
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Pappus 3-5 mm long. |
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(13) |
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12 (11) |
Stems 30-60 cm tall; leaves nearly glabrous or sparsely puberulous. |
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Aster indicus |
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Stems 50-100 cm tall; leaves hispidulous, rough to touch. |
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Aster shimadai |
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13 (11) |
Leaves pinnately nerved, glabrous. |
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Aster taiwanensis |
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Leaves conspicuously trinerved, not entirely glabrous. |
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(14) |
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14 (13) |
Leaves ovate; involucres turbinate. |
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Aster ovalifolius |
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Leaves oblong-lanceolate to lanceolate; involucres campanulate to hemispheric. |
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(15) |
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15 (14) |
Leaves scarcely puberulous or nearly glabrous. |
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Aster ageratoides |
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Leaves densely villose or hirsute. |
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Aster lasiocladus |
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List of lower taxa
Related Links (opens in a new window) |
Treatments in Other Floras @ www.efloras.org
Other Databases
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