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cluster yellow tops

alkali yellowtops

Habit Annuals, to 200+ cm (delicate or robust, glabrate or glabrous). Annuals, 18–70(–90) cm (delicate or robust, mostly glabrous).
Stems

erect.

usually erect (tufted-pubescent at nodes).

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.

sessile;

bladeslinear-lanceolate to lanceolate, 30–90 × 6–22 mm, bases barely connate, margins strongly to weakly serrate or spinulose-serrate.

Involucres

oblong and cylindric or angular, 3.8–4.5 mm.

urceolate or oblong, 6–7 mm.

Ray florets

0–1;

laminae pale yellow or whitish, oblique or suborbiculate, 0.5–1 mm.

0 or 1, laminae yellow, ovate, 1.5–2.5 mm (apices notched).

Disc florets

0–1(–2);

corolla tubes 0.5–1.4 mm, throats campanulate, 0.5–0.8 mm.

5–6(–8);, corolla tubes 0.8–1.3 mm, throats funnelform, 1.2–1.7 mm.

Phyllaries

usually 2, oblong (closely investing and falling with mature cypselae).

3, elliptic, obovate, or oblong-obovate.

Calyculi

0.

of 2 linear-lanceolate bractlets 1–3 mm.

Heads

30–300+, in tight, axillary, sessile glomerules (receptacles of glomerules setose).

(10–)15–100+, in tight subglomerules in corymbiform arrays.

Cypselae

oblanceoloid to subclavate, 2–2.6 mm (rays longer);

pappi 0.

oblanceolate, linear, or oblong, 2.8–3.6 mm (those of rays longer by ca. 0.2 mm), pappi 0.

2n

= 36.

= 36 (18).

Flaveria trinervia

Flaveria campestris

Phenology Flowering Mar–Dec. Flowering May–Nov.
Habitat Near water, saline and gypseous areas Saline soils, lake, pond, stream margins, flood plains, and disturbed pastures
Elevation 0–1900 m (0–6200 ft) 1000–1800 m (3300–5900 ft)
Distribution
from FNA
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)]
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; KS; MO; NM; OK; TX; UT
[WildflowerSearch map]
[BONAP county map]
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.)

Flaveria campestris is distinguished by subglomerulate capitulescences with 5–6(–8) florets per head, subtended by 3 leafy bracts, keeled phyllaries, and linear-lanceolate leaves with serrate or spinulose-serrate margins, and its distribution. The prevalence of F. campestris fluctuates greatly from year to year, generally depending on the existence of wet, saline habitat.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 21, p. 250. FNA vol. 21, p. 250.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Flaveriinae > Flaveria Asteraceae > tribe Heliantheae > subtribe Flaveriinae > Flaveria
Sibling taxa
F. bidentis, F. brownii, F. campestris, F. chlorifolia, F. floridana, F. linearis, F. mcdougallii
F. bidentis, F. brownii, F. chlorifolia, F. floridana, F. linearis, F. mcdougallii, F. trinervia
Synonyms Odera trinervia
Name authority (Sprengel) C. Mohr: Contr. U.S. Natl. Herb. 6: 810. (1901) J. R. Johnston: Proc. Amer. Acad. Arts 39: 287. (1903)
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