Flaveria bidentis
Flaveria
coastal plain yellowtops
yellowtops
erect.
(often purplish) erect or decumbent, branched distally or ± throughout.
petiolate (proximal, petioles 3–15 mm) or sessile (distal);
blades lanceolate-elliptic, 50–120(–180) × 10–25(–70) mm, bases (distal) connate, margins serrate 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.
oblong-angular, 5 mm.
oblong, urceolate, cylindric, or turbinate, 0.5–2 mm diam.
convex, epaleate (“receptacles” of glomerules sometimes setose).
0 or 1;
laminae pale yellow, ovate-oblique, to 1 mm (not or barely surpassing phyllaries).
0–1(–2), pistillate, fertile;
corollas yellow or whitish (laminae inconspicuous).
(2–)3–8;
corolla tubes ca. 0.8 mm, throats funnelform, 0.8 mm.
1–15, bisexual, fertile;
corollas yellow, tubes shorter than to about equaling funnelform to campanulate throats, lobes 5, ± deltate.
3(–4), oblong.
persistent, 2–6(–9) in ± 1 series (linear, concave, or boat-shaped, subequal).
of 1–2 linear bractlets 1–2 mm.
20–100+ in tight subglomerules in scorpioid, cymiform arrays.
radiate or discoid, usually in tight or loose aggregations in (often flat-topped) ± corymbiform arrays or glomerules.
oblanceolate or subclavate, 2–2.5 mm (those of ray florets 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).
= 18.
= 36.
Flaveria bidentis
Flaveria
In the United States, Flaveria bidentis often occurs on ballast and waste ground near wharfs and the shore, locations that suggest its introduction from sailing vessels. The species is widespread and well established in South America, where it is thought to be native. Its floral structure appears to be the least advanced among the annual species of Flaveria, the heads being in somewhat scorpioid arrays. Distinguishing characteristics are 3(–4) phyllaries, 2–8 florets per head, reduced ray corollas, pubescent stems, and lanceolate-elliptic, bluish green, sometimes pubescent leaves. Flaveria bidentis is probably most closely related to F. campestris and F. trinervia.
(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.)
1. Pappi usually of 2–4 scales or coroniform, rarely 0 | → 2 |
1. Pappi 0 | → 3 |
2. Leaf blades to 10–40 mm wide, bases connate-perfoliate; New Mexico, Texas | F. chlorifolia |
2. Leaf blades 2–7 mm wide, bases weakly connate; Arizona | F. mcdougallii |
3. Heads in tight, axillary glomerules ("receptacles" of glomerules setose) | F. trinervia |
3. Heads usually in corymbiform, paniculiform, or spiciform arrays, seldom in tight, axillary glomerules ("receptacles" of glomerules not setose). | → 4 |
4. Annuals | → 5 |
4. Perennials (annuals) | → 6 |
5. Heads in scorpioid cymiform arrays; ray laminae to 1 mm; Alabama, Florida, Georgia | F. bidentis |
5. Heads in corymbiform arrays; ray laminae 1.5–2.5 mm; sc, sw United States | F. campestris |
6. Calyculus bractlets surpassing involucres (sw coast, Florida) | F. floridana |
6. Calyculus bractlets shorter than involucres | → 7 |
7. Ray laminae oblong-elliptic, 2 mm; disc florets (5–)7–10; Texas | F. brownii |
7. Ray laminae oval to obovate-spatulate, 2–3 mm; disc florets (2–)5–7(–8); Florida | F. linearis |
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