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(Last Modified On 6/6/2013)
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(Last Modified On 6/6/2013)
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Species
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Erigeron annuus (L.) Pers
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PlaceOfPublication
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Syn. P1. 2: 431. 1807.
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Synonym
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Aster annuus L., Sp. PI. 875. 1753. TYPE: not seen. Aster stenactis Krause in Sturm, Deutschl. Fl., ed. 2, 13: 54. 1905. TYPE: not seen.
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Description
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Erect short-lived perennial herb to 1 m tall with a sturdy fibrous root and a small ephemeral rosette; stems striate-angled, puberulent with ascending, some- times long and spreading, stout-based hairs. Basal leaves spatulate, the basal 2/A narrowed into a slender petiole, slightly expanded and clasping at the base, the blades dentate with callose-mucronate teeth, scabrous above with sharp ascending hairs, beneath with some long white stiff hairs; stem leaves sessile, glabrescent, longer towards the middle of the stem (to 9 cm long and 15 mm wide) becoming smaller, entire and lanceolate towards the apex, the midvein prominent and flanked by a pair of weaker veins and another pair close to the margin. Inflores- cence an irregular corymb or panicle of few to many heads; peduncles variable in length, each with 1 or 2 scalelike bracts along their length. Heads radiate; involucral bracts in two similar series, slightly imbricated, 3-4 mm long and 0.6-0.8 mm wide, tapering to an acute or acuminate sometimes elongate point, chartaceous with a relatively broad hyaline margin, pilose with conspicuous, ?glandular, thin-walled, large-celled hairs; receptacle 2.5-3 mm across, convex, manifestly alveolate; ray florets numerous in about 2 series, the corollas white, 5-10 mm long and 0.7 mm broad, apically notched or entire, the tube ca. 1 mm long, pubescent with ascending hairs, the style branches ca. 0.25 mm long, flattened and narrowly elliptical; disc florets numerous, yellow, 2-2.5 mm long, the tube ca. 1 mm long, the limb only slightly expanded, tubular-campanulate, prominently angled, the upper half comprising 5 thick-margined deltoid teeth, the anthers 0.6-0.7 mm long, not exserted, the appendages narrow. Achene compressed with two veins thickening the margins, densely pubescent, stramineous or greenish; pappus in 2 series, the inner of fine strigulose bristles not exceeding the disc florets, the outer of short, united scales usually much shorter than the achene, the achenes of the ray florets with scales only and lacking bristles.
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Habit
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herb
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Note
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This species is distinct from other Panamanian species in its robust, coarse habit and in its showy, numerous white ligules. It is distinct from most species of Erigeron of other areas in its dimorphic achenes, those of the ray florets with a pappus of scales and those of the disc florets with both scales and bristles.
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Distribution
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native to southern Canada and the adjacent United States but is naturalized southward and in Europe. In Panama it is known in Chiriqui Province at upper elevations where it is a frequent weed of gardens, cafetales, and towns.
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Common
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Daisy fleabane
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Specimen
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CHIRIQUI: Cerro Punta, Godfrey 67327 (MO). 2.2 mi below Cerro Punta, ca. 6000 ft, Luteyn 895 (MO). 6.7 mi W of Boquete, 8000 ft, Luteyn 1506 (MO). Audubon Cabin, Nueva Suiza, Partch 69-9 (MO). 2.5 mi S of Cerro Punta, 5500 ft, Sawyer 1 March 1967 (MO). Bambito, 1 mi SW of Cerro Punta, 5600 ft, Tyson 5620 (MO). Ca. halfway between Cerro Punta and Bambito, ca. 5600 ft, Wilbur et al. 10950 (MO).
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