General:
Biennial herb from a stout taproot; forming rosette in first year and erect stiff stem in second; hairy with glandular and greyish, stiff hairs, also with spreading, reddish hairs; stems 30-150 cm tall, simple or branched.

Leaves:
Stem leaves alternate, ascending or spreading, narrowly lanceolate to oblong, 5-20 cm long, the largest 1-2.5 cm wide, entire to toothed, somewhat lobed toward base, densely or sparsely hairy; lower leaves stalked, the upper ones more or less unstalked.

Flowers:
Inflorescence a dense spike, the buds erect, opening in the evening, subtended by large bracts or reduced leaves; hypanthium 2-4 cm long; petals yellow, fading duller or orange, 1-2.5 (3) cm long; sepals 1.2-2 (2.8) cm long, green or yellowish, rarely reddish, bent back when in flower, the free tips in bud 1-3 mm long; stamens almost the length of petals and style, the anthers 4-6 mm long; stigma lobes 4, linear, 4-7 mm long.

Fruits:
Capsules, erect, narrowly lanceolate, 2.5-4 cm long, 4-6 mm wide, more or less straight, 4-chambered, hairy; seeds 1-2 mm long, angled, irregularly pitted.

Source:  The Illustrated Flora of British Columbia

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration Source:  The Illustrated Flora of British Columbia

Flower Colour:
Yellow

Blooming Period:
Late Spring

Fruit/Seed characteristics:
Colour: Brown
Present from Summer to Fall

Source:  The USDA

Synonyms and Alternate Names:
Oenothera albinervis R.R. Gates
Oenothera angustissima R.R. Gates
Oenothera biennis subsp. caeciarum Munz
Oenothera biennis subsp. centralis Munz
Oenothera biennis var. canescens Torr. & A. Gray
Oenothera biennis var. hookeri (Torr. & A. Gray) B. Boivin
Oenothera biennis var. oakesiana A. Gray
Oenothera biennis var. pycnocarpa (Atk. & Bartlett) Wiegand
Oenothera canovirens Steele
Oenothera cruciata var. stenopetala (E.P. Bicknell) Fernald
Oenothera depressa Greene
Oenothera hookeri Torr. & A. Gray
Oenothera hookeri subsp. montereyensis Munz
Oenothera muricata L.
Oenothera parviflora subsp. angustissima (R.R. Gates) Munz
Oenothera parviflora var. angustissima (R.R. Gates) Wiegand
Oenothera parviflora var. oakesiana (A. Gray) Fernald
Oenothera pycnocarpa Atk. & Bartlett
Oenothera strigosa subsp. canovirens (Steele) Munz
Oenothera villosa subsp. canovirens (Steele) W. Dietr. & P.H. Raven