22.
Helianthus hirsutus
Rafinesque, Ann. Nat. 1: 14. 1820.
Hairy sunflower
Helianthus hirsutus
var.
stenophyllus
Torrey & A. Gray;
H. hirsutus
var.
trachyphyllus
Torrey & A. Gray;
H. stenophyllus
(Torrey & A. Gray) E. Watson
Perennials,
100—200 cm (rhi-zomatous).
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).
Heads
1—7.
Peduncles
1—5 cm.
Involucres
hemispheric, 10—25 mm diam.
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.
Paleae
7—10 mm, 3-toothed (apices yellowish, hairy).
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.
Cypselae
4—4.5 mm, glabrate or distally puberulent;
pappi
of 2 aristate scales 2.5—3.2 mm.
2
n
= 68.
Flowering late summer—fall. Dry, open sites, woodland edges, roadsides; 10—900+ m; Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mich., Minn., Miss., Mo., Nebr., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va., Wis.; Mexico (Coahuila, Nuevo León).
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.
