Flora of North America species comparison

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Helianthus hirsutus

hairy sunflower
Habit Perennials, 100–200 cm (rhizomatous).
Stems

erect, hirsute.
Leaves

cauline; mostly opposite;

petioles 0.4–2 cm;

blades (3-nerved from bases) lanceolate to ovate, 6.5–18 × 1–8 cm, bases truncate to broadly rounded or cuneate, margins subentire to serrate (flat), abaxial faces ± hirsute, gland-dotted (adaxial not gland-dotted).
Peduncles

1–5 cm.
Involucres

hemispheric, 10–25 mm diam.
Ray florets

10–15;

laminae 15–20 mm.
Disc florets

40+;

corollas 5.5–6.5 mm, lobes yellow;

anthers dark brown or black, appendages dark or yellowish.
Phyllaries

18–25 (usually loose, spreading, not reflexed), lanceolate, 7–12 × 2.5–3.5 mm, (margins ciliate) apices acute to short-acuminate, abaxial faces not gland-dotted.
Heads

1–7.
Cypselae

4–4.5 mm, glabrate or distally puberulent;

pappi of 2 aristate scales 2.5–3.2 mm.
Paleae

7–10 mm, 3-toothed (apices yellowish, hairy).
2n

= 68.

Helianthus hirsutus
Phenology Flowering late summer–fall.
Habitat Dry, open sites, woodland edges, roadsides
Elevation 10–900+ m (0–3000+ ft)
Distribution
from FNA
AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MD; MI; MN; MO; MS; NC; NE; NY; OH; OK; PA; SC; TN; TX; VA; WI; WV; ON; Mexico (Coahuila, Nuevo León)
[WildflowerSearch map]
[BONAP county map]
Discussion

Helianthus hirsutus is distinguished from H. strumosus by hairy stems and usually yellow (as opposed to dark) anther appendages, and from H. divaricatus by petioles and leaf blades 3-nerved distal to bases. Mexican plants of H. hirsutus are sometimes labeled with the synonymous H. leptocaulis (S. Watson) S. F. Blake, and plants from Mexico and the southwestern United States often have leaf bases cuneate rather than truncate.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 21, p. 157.
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. bolanderi, 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. 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
Synonyms H. hirsutus var. stenophyllus, H. hirsutus var. trachyphyllus, H. stenophyllus
Name authority Rafinesque: Ann. Nat. 1: 14. (1820)
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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