Helianthus annuus L.
sunflower
Erect annual herb, with stout taproot. Stems scabrid, not branched, 0.4- c. 2 m tall. Lower and mid cauline lvs hispidulous, petiolate, ovate- elliptic to ovate-triangular, acute to acuminate, obtuse or truncate to cordate at base, serrate, 6-20-(30) cm long; upper cauline lvs similar to lower, but uppermost alternate, smaller and narrower. Capitula (8)-10-20-(30) cm diam., solitary. Involucral bracts in 2-3 rows, moderately to densely scabrescent, ciliate, ovate to ovate-triangular, aristate, c. 3-6 × (0.8)-1.5-2 cm. Receptacle ± flat; scales membranous, the larger with dark ciliate apices. Ray florets (15)-20-50; disc florets numerous, brownish yellow. Achenes oblong-obovoid, narrowed to base, hairy, 10-15 mm long; pappus 0.
N.: Waipoua (N. Auckland); S.: vicinity of Christchurch.
N. America 1880
Casual of waste places.
FL Jan-Mar.
Sunflower is cultivated as an ornamental and also for the seeds and the oil extracted from them. The few collections of the sp. from the wild represent depauperate plants; cultivated plants are generally 1.5 m or more tall, with lvs 30 cm or more long and heads often exceeding 30 cm diam.
