Flowers solitary in upper leaf-axils, without bracteoles; usually actinomorphic. Hypanthium up to 4 cm long [or absent]. Sepals 4, not persistent. Petals 4, white, pink, [yellow or red]. Stamens 8. Ovary 4-locular.
Fruit a terete capsule, 4-locular; seeds usually ± obovoid, numerous, usually comose.
| | Key to the species | |
| 1 | Plants ascending to erect, with stems >30 cm high | 2 |
| Plants mat-forming, sometimes with ascending stems to 15 cm high | 9 |
| 2 | Seeds with pale cellular rim | Epilobium gunnianum |
| Seeds without pale cellular rim
Back to 1 | 3 |
| 3 | Stems softly hairy with spreading hairs | 4 |
| Stems with short crisped hairs
Back to 2 | 5 |
| 4 | Leaves usually >10 mm wide, margins serrulate with 15 or more teeth each side; petals 9–20 mm long | Epilobium hirsutum |
| Leaves to 8 mm wide, margins coarsely toothed with up to 12 teeth each side; petals 3–8 mm long
Back to 3 | Epilobium hirtigerum |
| 5 | Inner surface of hypanthium glabrous; fruiting pedicel 15–50 mm long | Epilobium sarmentaceum |
| Inner surface of hypanthium with ring of hairs; fruiting pedicel, less than 30 mm long
Back to 3 | 6 |
| 6 | Petals 3–5 mm long; papillae on seed surface in longitudinal lines | Epilobium ciliatum |
| Petals 3–14 mm long; papillae on seed surface not in lines
Back to 5 | 7 |
| 7 | Glandular hairs present in the flowering region; leaves almost glabrous to hirsute, linear or lanceolate to narrow-ovate | Epilobium billardiereanum |
| Glandular hairs absent from flowering region; leaves glabrous except for a few crisped hairs on margins and veins, narrow-lanceolate to ovate
Back to 6 | 8 |
| 8 | Leaves narrow-lanceolate to lanceolate, with up to 25 small well-spaced teeth on each side; inflorescences nodding | Epilobium pallidiflorum |
| Leaves narrow-ovate to ovate, with up to 40 small regular teeth on each side; inflorescences erect
Back to 7 | Epilobium billardiereanum |
| 9 | Seeds with pale cellular rim, not comose | Epilobium curtisiae |
| Seeds without pale cellular rim, comose
Back to 1 | Epilobium tasmanicum |
