Oenothera biennis L.
evening primrose
Biennial, taprooted herb. Stems to c. 1 m tall, sometimes branched, with scattered long white hairs, with or without hairs with bulbous red bases. Rosette lvs long-petiolate; lamina to 27 × 4 cm, lanceolate to elliptic, with short curly hairs, sometimes hairs ± appressed; midrib pale; margins subentire to denticulate or sinuate; base cuneate to attenuate; apex acute. Cauline lvs with winged petiole or apetiolate; lamina smaller but otherwise similar. Infl. many- or few-flowered, its stem simple or branched; rachis and ovary densely clothed in glandular hairs. Fls crepuscular. Floral tube 3-4.5 cm long, slender, densely clothed in glandular hairs. Buds narrow-lanceolate, erect. Sepals to 3.5 cm long, glandular-hairy; apices mucronate, not or only slightly divergent. Petals 2-3.5 cm long, broad-obovate, yellow. Style exserted by 0.7-2.5 cm, < to > stamens. Capsules 1.5-3.3 cm long, cylindric but widening slightly towards base, ribbed, densely clothed in glandular hairs. Seeds 1.5-2 mm long, sharply angular, very irregular.
N.: Wellington; S.: Blenheim, Christchurch.
N. America 1940
FL Nov-Mar.
Wild plants vary; CHR 322101, Blenheim, Healy, 31.3.1977, has small, broad, cauline lvs (rosette lvs lacking on specimen) and no pilose hairs. The lack of red-based hairs, however, means that it is best referred to O. biennis.
O. biennis is closely related to O. glazioviana and some early records of O. biennis may well be in error for that sp. The first confirmed record is that of Allan (1940) who briefly described and illustrated O. biennis; this record is accepted because he also distinguished O. glazioviana (as O. lamarckiana De Vries). Early records of O. suaveolens and O. grandiflora may be based on plants of O. biennis or O. glazioviana.
