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(Last Modified On 6/17/2013)
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(Last Modified On 6/17/2013)
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Species
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Sigesbeckia jorullensis H.B.K.
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PlaceOfPublication
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Nov. Gen. Sp. PI. 4: 284. 1820.
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Note
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TYPE: Mexico Bonpland, (P).
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Description
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Erect, short-lived branched herb to 1 m tall; stems drying striate, with spreading, multicellular, glandular hairs; roots fibrous. Leaves opposite, to 10 cm long (includingpetiole), apically acute, basally rounded or truncate, acumi- nate into the petiole, the margins serrate, the principal veins 3 from the base, puberulent above and beneath with scattered, multicellular hairs, some of these gland-tipped, the surface eglandular; petiole prominently winged, basally expanded-auriculate and connate in pairs; leaves near the inflorescence much smaller, sessile with cuneate bases. Inflorescence an open, several-many-flowered panicle; peduncles slender, copiously glandular with erect hairs; bracts foliaceous; bractlets scalelike, not opposed. Heads small, inconspicuously radiate; outer involucral bracts 5, spreading, linear-oblanceolate, apically obtuse or rounded and slightly expanded, 8-18 mm long, ca. 1 mm wide, copiously stipitate-glandular, the inner 8 involucral bracts ca. 3 mm long, cucullate and enveloping the ray flower, apically acute or acuminate, 3-nerved, dorsally stipitate-glandular; paleas broadly ovate, scarious, enveloping the flower, the apex stipitate glandular; receptacle conical; ray florets 4-5 mm long, the corolla yellow, the cobwebby, apically glandular tube forming about half the length, the tube with an apical lobe opposite the ligule, the ligule recurved, broadly elliptical, 3-nerved, apically sinuate 3-dentate, the style branches darker than the style, the style base not expanded, the ovary fertile, 1.5 mm long, irregular-fabiform, glabrous or minutely cobwebby, the pappus wanting, the carpopodium relatively large; disc florets ca. 8, ca. 4 mm long, the corolla yellowish, ca. 2 mm long, the tube with erect hairs, forming half the length, the limb campanulate-angular, lobed 1/3?/-- way down, the lobes deltoid, glabrous, the stamens inserted at the apex of the tube, the anthers green, the appendages ovate, the adjacent basal auricles connate, ?toothed, the style branches flattened, the basal half pilose, the apex deltoid, the style base not expanded, the nectary cylindrical, the ovary fabiform, glabrous, slightly compressed laterally, the apex a contracted umbo surmounted by the nectary. Fruit a utricle or achene, black, minutely striate, ca. 2 mm long, plump and the angles rounded, slightly beaked, sometimes falling enclosed by- the palea; carpopodium inconspicuous; pappus wanting.
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Note
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Sigesbeckia jorullensis is distinguished by the linear, stipitate glandular involucral bracts. Several features of the plants are of interest, e.g., the ligulelike corolla projection at the adaxial apex of the corolla tube, the inner series of involucral bracts which enfold the ray flowers much like paleas, and the insertion of the stamen filaments which at no stage flex in preparation for anthesis.
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Distribution
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ranges from southern Chile to northern Mexico and occurs on Hispaniola.
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Note
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A related species, S. agrestis Poepp. & Engl., may be expected in Panama. It differs in its achenes being square rather than ovate in cross section, in its usually succulent stems, and in its usually shorter outer series of involucral bracts. Sigesbeckia jorullensis is a species of upper elevations; S. agrestis is a species of lowlands.
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Specimen
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CHIRIQUI: 2.7 mi NW of Rio Chiriqui Viejo, W of Cerro Punta, Croat 22418 (MO). Bajo Chorro, Boquete District, 6000 ft, Davidson 150 (GH). Cerro Pando, valley of the upper Rio Chiriqui Viejo, White 45 (MO).
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