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(Last Modified On 6/6/2013)
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(Last Modified On 6/6/2013)
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Genus
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Erigeron L.
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PlaceOfPublication
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Gen. P1., ed. 5. 956. 1754.
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Note
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TYPE: E. uniflorus L.
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Description
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Annual or perennial pubescent herbs, erect or prostrate, sometimes caespitose, sometimes woody, some species with rhizomes. Leaves alternate, sometimes forming rosettes, simple, entire or variously divided, herbaceous, sessile but the lower portion of the leaf often narrowed into a petiolelike region. Inflorescence scapose, solitary, or variously paniculate or corymbose. Heads radiate or nearly disciform; involucre campanulate or hemispheric, the involucral bracts in about 2 mostly subequal series, somewhat imbricate, herbaceous with a hyaline margin, narrow and apically attenuate, acute or subulate; receptacle flat to slightly convex, naked, alveolate or smooth; ray florets numerous, usually in about 2 series, fertile, the ligule slender to linear, rarely broad, exceeding the style and pappus, apically denticulate or entire; disc florets numerous, the corolla yellowish with a campanulate to infundibuliform, sometimes only slightly expanded limb and 5 regular apical teeth, the anthers basally obtuse, rarely auriculate, the appendage obtuse, oblong or almost linear, the style branches more or less flattened, dorsally papillose-pilose or verrucose with margins thickened, its apical appendages triangular lanceolate to linear, the ovary fertile or a few in the center abortive. Achene compressed, ovoid or ellipsoid, glabrous or pubescent with two nerves thickening the margins and sometimes 2-3 additional less conspicuous nerves on the sides; pappus of 1 or 2 series, the inner of fine strigulose bristles, the outer of shorter bristles, scales or wanting.
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Habit
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herbs
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Note
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Erigeron is distinguished from Aster by the absence of an apical expansion of the herbaceous nerve of the involucral bracts and from Conyza in having ligules longer than the pappus or disc florets. Erigeron and Conyza are combined by some workers. In general, species of Erigeron may be recognized by the many white or bluish (never yellow) slender ray and yellowish disc florets. The nearly similar involucral bracts are arranged in about two imbricate series.
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Distribution
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The genus Erigeron includes about 200 species almost worldwide in distribu- tion but with the greatest number of species in North America.
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Common
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Fleabanes
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Key
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a. Large erect plants to 1 m tall; stem leaves more than 6 cm long; stems becoming 3 mm thick; pappus of the ray florets composed of both bristles and scales ...... 1. E. annuus aa. Decumbent or scapose plants less than 30 cm tall; stem leaves less than 5 cm long; stems less than 2-mm thick; pappus of the ray florets composed only of bristles in 1 or 2 series. b. Plants scapose; stem leaves less than 10 mm long; involucral bracts more than 4 mm long; pappus as long as the disc florets; disc florets more than 3 mm long ...... 2. E. cuneifolius bb. Plants decumbent; stem leaves more than 10 mm long; involucral bracts less than 4 mm long; pappus exceeding the disc florets; disc florets less than 3 mm long ...... 3. E. karvinskianus
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