Flaveria trinervia |
Flaveria |
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cluster yellow tops |
yellowtops |
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Habit | Annuals, to 200+ cm (delicate or robust, glabrate or glabrous). | Annuals, perennials, or subshrubs, to 200+ cm [trees to 400 cm] (usually ± succulent, herbage usually glaucous). | ||||||||||||||||||||||||||||
Stems | erect. |
(often purplish) erect or decumbent, branched distally or ± throughout. |
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Leaves | petiolate (proximal, petioles 10–20 mm) or sessile (distal); blades lanceolate or oblanceolate to elliptic or subovate, 30–150 × (7–)10–40 mm, bases (distal) connate, margins serrate, serrate-dentate, or spinulose-serrate. |
cauline; opposite (decussate); petiolate or sessile (weakly connate to connate-perfoliate); blades (often 3-nerved) oblong-ovate to lanceolate or linear, margins entire, serrate, or spinulose-serrate, faces glabrous or short-pubescent. |
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Involucres | oblong and cylindric or angular, 3.8–4.5 mm. |
oblong, urceolate, cylindric, or turbinate, 0.5–2 mm diam. |
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Receptacles | convex, epaleate (“receptacles” of glomerules sometimes setose). |
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Ray florets | 0–1; laminae pale yellow or whitish, oblique or suborbiculate, 0.5–1 mm. |
0–1(–2), pistillate, fertile; corollas yellow or whitish (laminae inconspicuous). |
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Disc florets | 0–1(–2); corolla tubes 0.5–1.4 mm, throats campanulate, 0.5–0.8 mm. |
1–15, bisexual, fertile; corollas yellow, tubes shorter than to about equaling funnelform to campanulate throats, lobes 5, ± deltate. |
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Phyllaries | usually 2, oblong (closely investing and falling with mature cypselae). |
persistent, 2–6(–9) in ± 1 series (linear, concave, or boat-shaped, subequal). |
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Calyculi | 0. |
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Heads | 30–300+, in tight, axillary, sessile glomerules (receptacles of glomerules setose). |
radiate or discoid, usually in tight or loose aggregations in (often flat-topped) ± corymbiform arrays or glomerules. |
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Cypselae | oblanceoloid to subclavate, 2–2.6 mm (rays longer); pappi 0. |
(black) weakly compressed, narrowly oblanceolate or linear-oblong (usually 10-nerved, glabrous); pappi usually 0, sometimes persistent, of 2–4 hyaline scales, or coroniform (of connate scales). |
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x | = 18. |
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2n | = 36. |
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Flaveria trinervia |
Flaveria |
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Phenology | Flowering Mar–Dec. | |||||||||||||||||||||||||||||
Habitat | Near water, saline and gypseous areas | |||||||||||||||||||||||||||||
Elevation | 0–1900 m (0–6200 ft) | |||||||||||||||||||||||||||||
Distribution |
AZ; CA; FL; MA; MO; NM; TX; VA; HI; West Indies; Central America (British Honduras); South America (Brazil, Ecuador, Peru, Venezuela); Africa [Probably introduced in Asia (India, Middle East)]
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United States; Mexico; Central America; South America; West Indies (Greater Antilles); Asia (India); Africa; Australia |
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Discussion | Flaveria trinervia is widespread and weedy; it often occurs in saline, gypseous, disturbed areas near permanent or ephemeral water sources in southern Florida and from Texas to southern California. It occurs also in scattered locations in some eastern states and has been reported from Alabama. The heads of Flaveria trinervia, which usually contain just one floret, are either radiate or discoid; radiate heads tend to occur on the periphery of setose glomerules. Reduction of some of the floral features, including number of florets [0–1(–2)], phyllaries per head (2), and size of ray laminae, suggest that F. trinervia may be the most derived species in the genus. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species 21 (8 in the flora). Members of Flaveria are frequently found in alkaline, saline, and gypseous soils, often in disturbed and moist areas. Heads of Flaveria may be either radiate or discoid; when both are present in the same capitulescence, the discoid heads tend to be central and the radiate heads peripheral. Many species of Flaveria have persistent sheathing leaf bases that ring the stems after the leaves have fallen. Flaveria is notable because certain species exhibit C3 photosynthesis, some C3–C4 (intermediate) photosynthesis, and others (F. brownii, F. bidentis, F. campestris, and F. trinervia in the United States) classic C4 photosynthesis. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 21, p. 250. | FNA vol. 21, p. 247. | ||||||||||||||||||||||||||||
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Flaveriinae > Flaveria | Asteraceae > tribe Heliantheae > subtribe Flaveriinae | ||||||||||||||||||||||||||||
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Synonyms | Odera trinervia | |||||||||||||||||||||||||||||
Name authority | (Sprengel) C. Mohr: Contr. U.S. Natl. Herb. 6: 810. (1901) | Jussieu: Gen. Pl., 186. (1789) | ||||||||||||||||||||||||||||
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