45.
Helianthus nuttallii
Torrey & A. Gray, Fl. N. Amer. 2: 324. 1842.
Nuttall's sunflower, hélianthe de Nuttall
Perennials
, 100—400 cm (rhizom-atous).
Stems
(usually yellow-brown or greenish, sometimes glaucous) erect, glabrous, hispid, ± hirsute, or scabrous.
Leaves
cauline; all or mostly opposite to mostly alternate; petioles 0.5—1.5 cm; blades light to dark green, 3-nerved distal to bases) ± lanceolate to ± ovate, 4—20 × 0.8—4 cm, bases cuneate, margins entire or ± serrate (flat), abaxial faces hispid to hispidulous or tomentulose to villous-tomentose, gland-dotted.
Heads
1—6.
Peduncles
1—18 cm.
Involucres
hemispheric, 10—20 mm diam.
Phyllaries
30—38 (loose, spreading), lanceolate to lance-ovate, 8—16 × 1.5—3 mm, (margins ciliate) apices acute to acuminate, abaxial faces usually ± strigose, rarely glabrate, not gland-dotted.
Paleae
8—12 mm, 3-toothed.
Ray florets
10—21; laminae 20—25 mm (abaxial faces not gland-dotted).
Disc florets
60+; corollas 5—7 mm, lobes yellow; anthers dark brown to black, appendages yellow
. Cypselae
3—5 mm, glabrate;
pappi
of 2 aristate scales 2.2—4.5 mm plus 0—2 lanceolate scales 0.5—1 mm.
2
n
= 34 (subspecies unknown).
Subspecies 3 (3 in the flora): North America.
