Synonyms: Gaura APNI*
Description: Annual or perennial herbs or subshrubs, sometimes stem reduced.
Leaves basal or alternate, often attenuate at the base, and reducing in size up stem, margins often undulate and ± entire to pinnatifid.
Flowers solitary in the upper bract-like leaf axils or in spike-like racemes; often conspicuous, usually opening in the evening and fading the next morning; actinomorphic, 4-merous. Hypanthium usually long and slender, not persistent. Sepals not persistent. Petals usually yellow, pink or white, often becoming reddish with age.
Fruit a capsule; seeds numerous.
Distribution and occurrence: World: c. 120 species, America. Australia: 13 species (naturalized), all States.
**O. triloba is doubtfully recorded as naturalized in N.S.W.; however, the record is not substantiated. One record only from near Inverell, in 1941.
Text by J. M. Dalby Taxon concept:
Taxa not yet included in identification key
Oenothera biennis
| Key to the species | |
1 | Fruit indehiscent and few-seeded | 2 |
| Fruit dehiscent, usually many-seeded | 3 |
2 | Plant softly hairy; flowers actinomorphic; petals less than 5 mm long | Oenothera curtiflora |
| Plant coarsely hairy; flowers zygomorphic; petals more than 5 mm long Back to 1 | Oenothera lindheimeri |
3 | Capsules distinctly clavate, the narrow basal part sterile; flowers pink or white | 4 |
| Capsules cylindrical to ovoid, fertile to the base; flowers yellow or white Back to 1 | 6 |
4 | Petals 20–35 mm long | 5 |
| Petals c. 10 mm long Back to 3 | Oenothera rosea |
5 | Stems with long spreading hairs | Oenothera tetraptera |
| Stems without long spreading hairs Back to 4 | Oenothera speciosa |
6 | Capsules ovoid with 4 broad wings | Oenothera triloba |
| Capsules more or less cylindrical, without wings Back to 3 | 7 |
7 | Hypanthium 7 cm or more long | 8 |
| Hypanthium less than 7 cm long Back to 6 | 9 |
8 | Cauline leaves ovate to elliptic; leaves subtending the fruit shorter than the capsules | Oenothera longiflora |
| Leaves narrow-lanceolate; leaves subtending the fruit longer than the capsules Back to 7 | Oenothera affinis |
9 | Stems with some hairs dark red at base, stems appear red-spotted; flowers in a spike | Oenothera glazioviana |
| Stems with hairs not dark red at base, stems not appearing red-spotted; flowers solitary in upper leaf axils Back to 7 | 10 |
10 | Cauline leaves sinuate-pinnatifid | Oenothera laciniata |
| Cauline leaves sparsely toothed Back to 9 | 11 |
11 | Plants hairy | 12 |
| Plants glabrous or sparsely hairy Back to 10 | 13 |
12 | Plants with coarse, moderately stiff hairs; cauline leaves obovate to oblanceolate, tapering to the base | Oenothera drummondii |
| Plants with fine, soft hairs; cauline leaves narrow-lanceolate to elliptic, sessile Back to 11 | Oenothera mollissima |
13 | Hypanthium less than 2 cm long, petals less than 1.2 cm long; basal leaves usually less than 8 cm long, rosette often not persistent | Oenothera indecora |
| Hypanthium more than 2 cm long, petals more than 1.2 cm long; basal leaves mostly more than 8 cm long, rosette always present Back to 11 | Oenothera stricta |
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