Flora of North America species comparison

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Helianthus bolanderi

Bolander's sunflower, serpentine sunflower
Habit Annuals, 60–150 cm.
Stems

erect, hispid to hirsute.
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.
Peduncles

3–13 cm.
Involucres

hemispheric, 17–25 mm diam.
Ray florets

12–17;

laminae 14–20 mm.
Disc florets

75+ (discs usually 2+ cm diam.);

corollas 5–7 mm, lobes usually reddish;

anthers dark, appendages dark (style branches reddish).
Phyllaries

10–18, usually lanceolate to lance-ovate, 9–27 × (3–)3.5–5 mm (often surpassing discs), apices gradually attenuate, abaxial faces hirsute.
Heads

1–3.
Cypselae

3.5–4.5 mm, glabrate;

pappi of 2 lanceolate scales 1.7–3 mm.
Paleae

9.5–10.5 mm, 3-toothed (middle teeth subulate, surpassing discs, apices glabrous).
2n

= 34.

Helianthus bolanderi
Phenology Flowering summer–early fall.
Habitat Grassy, often disturbed sites
Elevation 10–1200 m (0–3900 ft)
Distribution
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
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.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Helianthinae > Helianthus
Sibling taxa
H. agrestis, H. angustifolius, H. annuus, H. anomalus, H. argophyllus, H. arizonensis, H. atrorubens, H. californicus, H. carnosus, H. ciliaris, H. cusickii, H. debilis, H. decapetalus, H. deserticola, H. divaricatus, H. eggertii, H. exilis, H. floridanus, H. giganteus, H. glaucophyllus, H. gracilentus, H. grosseserratus, H. heterophyllus, H. hirsutus, H. laciniatus, H. laevigatus, H. longifolius, H. maximiliani, H. microcephalus, H. mollis, H. neglectus, H. niveus, H. nuttallii, H. occidentalis, H. paradoxus, H. pauciflorus, H. petiolaris, H. porteri, H. praecox, H. pumilus, H. radula, H. resinosus, H. salicifolius, H. schweinitzii, H. silphioides, H. simulans, H. smithii, H. strumosus, H. tuberosus, H. verticillatus, H. ×laetiflorus
Name authority A. Gray: Proc. Amer. Acad. Arts 6: 544. (1865)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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