Flaveria bidentis
Flaveria mcdougallii
coastal plain yellowtops
Mcdougall's yellowtops
erect.
erect.
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.
sessile;
blades linear to narrowly linear-lanceolate, 50–110 × 2–7 mm, bases weakly connate, margins entire.
oblong-angular, 5 mm.
turbinate, 3 × 0.7 mm.
0 or 1;
laminae pale yellow, ovate-oblique, to 1 mm (not or barely surpassing phyllaries).
0.
(2–)3–8;
corolla tubes ca. 0.8 mm, throats funnelform, 0.8 mm.
2–6 (exserted conspicuously from involucres);
corolla tubes 1 mm, throats funnelform, 1.5 mm.
3(–4), oblong.
2–6, oblong.
of 1–2 linear bractlets 1–2 mm.
of 0–1 linear bractlets 1–3 mm.
20–100+ in tight subglomerules in scorpioid, cymiform arrays.
50–200+, in clusters in compound, corymbiform or paniculiform arrays.
oblanceolate or subclavate, 2–2.5 mm (those of ray florets longer);
pappi 0.
linear, 1.5 mm;
pappi coroniform (fringed scales), ca. 0.3 mm.
= 36.
= 36.
Flaveria bidentis
Flaveria mcdougallii
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.)
Flaveria mcdougallii is known only from four locations near shaded alkaline seeps and springs close to the Colorado River in the Grand Canyon of northern Arizona. Delimiting characteristics of F. mcdougallii include linear leaves with entire margins, pappi of crowns of scales, and the distribution. Morphologic character differences and experimental hybridization studies suggest that F. mcdougallii could well be assigned to a separate, monotypic genus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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