Helianthus laciniatus
Helianthus bolanderi
alkali sunflower
Bolander's sunflower, serpentine sunflower
erect, usually strigose or hispid to glabrate.
erect, hispid to hirsute.
cauline; opposite or alternate;
sessile;
blades (green or grayish, 1- or 3-nerved) lanceolate, 5–9 × 0.5–3.5 cm, bases ± cuneate, margins entire or irregularly toothed to lobed, faces strigose to strumose, gland-dotted (adaxial sometimes glaucous).
mostly cauline; mostly alternate;
petioles 1–4 cm;
blades lance-linear or lance-ovate to ovate, 3–15 × 2–6 cm, bases cuneate to truncate, margins usually serrate, abaxial faces sparsely hirsute, gland-dotted.
4–13 cm.
3–13 cm.
hemispheric, 10–24 mm diam.
hemispheric, 17–25 mm diam.
14–20;
laminae ca. 8–11 mm.
12–17;
laminae 14–20 mm.
40+;
corollas 4.8–5.8 mm, lobes reddish;
anthers purplish, appendages reddish (style branches yellow).
75+ (discs usually 2+ cm diam.);
corollas 5–7 mm, lobes usually reddish;
anthers dark, appendages dark (style branches reddish).
16–21, lanceolate, 6–7.5 × 1.8–2.5 mm (often subequal), (margins ciliate) apices acute, abaxial faces hispidulous or strigose to glabrate, gland-dotted.
10–18, usually lanceolate to lance-ovate, 9–27 × (3–)3.5–5 mm (often surpassing discs), apices gradually attenuate, abaxial faces hirsute.
1–9.
1–3.
2.7–3.5 mm, glabrate;
pappi of 2(–3) aristate scales 1.4–2.5 mm.
3.5–4.5 mm, glabrate;
pappi of 2 lanceolate scales 1.7–3 mm.
7–7.8 mm, entire or 3-toothed (apices obtuse to acute, hispid-ciliate to glabrate).
9.5–10.5 mm, 3-toothed (middle teeth subulate, surpassing discs, apices glabrous).
= 34.
= 34.
Helianthus laciniatus
Helianthus bolanderi
Helianthus laciniatus reaches the northern extent of its range in New Mexico and Texas; it is relatively common in the Chihuahuan Desert areas of Mexico. It is similar to H. ciliaris; it usually has hairy stems as well as denser leaf indument that includes a greater number of subsessile, glandular hairs.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Helianthus bolanderi and H. exilis form a closely related pair of sister species that share the distinctive feature of having the middle teeth of the paleae glabrous and relatively elongated, surpassing the disc florets. As treated here, H. bolanderi corresponds to the “valley weed race” (C. B. Heiser 1949; L. H. Rieseberg et al. 1988); it is separated from the “serpentine foothill race,” here recognized as H. exilis. Heiser proposed that H. bolanderi originated through hybridization between H. annuus and H. exilis; molecular studies by Rieseberg et al. do not support this scheme. In an ironic twist, it appears that H. bolanderi may be undergoing “genetic assimilation” through hybridization with H. annuus (S. E. Carney et al. 2000).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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