Helianthus bolanderi |
Helianthus gracilentus |
|
---|---|---|
Bolander's sunflower, serpentine sunflower |
slender sunflower |
|
Habit | Annuals, 60–150 cm. | Perennials, 60–200 cm (taprooted). |
Stems | erect, hispid to hirsute. |
(reddish or purplish) erect, hairy. |
Leaves | 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. |
cauline; all or mostly opposite; petioles 0–3 cm; blades (1- or 3-nerved) lanceolate to lance-ovate, 5–11 × 2–3.5 cm, bases cuneate, margins entire or serrate, abaxial faces hispid, gland-dotted. |
Peduncles | 3–13 cm. |
2.5–30 cm. |
Involucres | hemispheric, 17–25 mm diam. |
hemispheric, 13–20 mm diam. |
Ray florets | 12–17; laminae 14–20 mm. |
13–21; laminae 15–25 mm (abaxial faces gland-dotted). |
Disc florets | 75+ (discs usually 2+ cm diam.); corollas 5–7 mm, lobes usually reddish; anthers dark, appendages dark (style branches reddish). |
50+; corollas 5–6 mm, lobes reddish; anthers reddish brown, appendages yellow or dull orange (style branches yellow). |
Phyllaries | 10–18, usually lanceolate to lance-ovate, 9–27 × (3–)3.5–5 mm (often surpassing discs), apices gradually attenuate, abaxial faces hirsute. |
20–25, lanceolate, 4–8 × 1.5–3 mm, (margins ciliate) apices acute, abaxial faces hispidulous, gland-dotted. |
Heads | 1–3. |
1–5. |
Cypselae | 3.5–4.5 mm, glabrate; pappi of 2 lanceolate scales 1.7–3 mm. |
3–4 mm, glabrate; pappi of 2 aristate scales 2.5–3 mm. |
Paleae | 9.5–10.5 mm, 3-toothed (middle teeth subulate, surpassing discs, apices glabrous). |
8–9 mm, subentire to weakly 3-toothed (apices acute, ciliate, gland-dotted). |
2n | = 34. |
= 34. |
Helianthus bolanderi |
Helianthus gracilentus |
|
Phenology | Flowering summer–early fall. | Flowering late spring–fall. |
Habitat | Grassy, often disturbed sites | Dry slopes |
Elevation | 10–1200 m (0–3900 ft) | 0–1800 m (0–5900 ft) |
Distribution |
CA; OR
|
CA; Mexico (Baja California)
|
Discussion | 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.) |
|
Source | FNA vol. 21, p. 149. | FNA vol. 21, p. 168. |
Parent taxa | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus | Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus |
Sibling taxa | ||
Name authority | A. Gray: Proc. Amer. Acad. Arts 6: 544. (1865) | A. Gray: Proc. Amer. Acad. Arts 11: 77. (1876) |
Web links |