Leaves alternate, opposite or sometimes whorled, ± sessile, decreasing in size up the stem, margins usually bearing small callus teeth.
Inflorescences terminal, cymose or flowers solitary. Sepals usually 5, persistent in fruit. Corolla campanulate or rotate, usually 5-lobed. Stamens usually 5; anthers withering before the flower opens, filaments expanded, ciliate, sometimes persistent in fruit. Ovary inferior, 2–5-locular; upper part of style with pollen presenting hairs.
| | Key to the species | |
| 1 | Flowers solitary; perennials growing in rock crevices in the McPherson Ra. or on the tablelands at higher altitudes | 2 |
| Flowers in cymose inflorescences (sometimes solitary in young or annual plants); annuals or perennials; widespread | 6 |
| 2 | Tufted, much-branched plants growing in rock crevices; flower stalks 1–5 cm long; corolla lobes 5–9 mm long; confined to the McPherson Range | 3 |
| Plants with spreading rhizomes and erect, stems mostly unbranched; flower stalks 3–40 cm long; corolla lobes 10–25 mm long; on the tablelands, mainly in subalpine areas
Back to 1 | 4 |
| 3 | Plants hirsute; leaves elliptic | Wahlenbergia scopulicola |
| Plants glabrous; leaves linear to narrow-elliptic
Back to 2 | Wahlenbergia glabra |
| 4 | Lower leaves 5–15 mm long, 1–2 mm wide; style usually 2-fid | Wahlenbergia densifolia |
| Lower leaves 10–50 mm long, 4–15 mm wide; style 2- or 3-fid
Back to 2 | 5 |
| 5 | Corolla blue; style 3-fid; leaves alternate, margins more or less flat | Wahlenbergia ceracea |
| Corolla purple; style usually 2-fid; leaves alternate or opposite, margins undulate
Back to 4 | Wahlenbergia gloriosa |
| 6 | Annuals with thin taproots; uppermost leaves and bracts ovate or lanceolate; lower leaves usually opposite, obovate to elliptic | 7 |
| Perennials developing thickened taproots (except for some annual Wahlenbergia tumidifructa); uppermost leaves and bracts oblong or linear; lower leaves opposite or alternate, broad or narrow
Back to 1 | 8 |
| 7 | Corolla lobes 0.5–5 mm long, 1–2 times as long as the tube; sepals oblong | Wahlenbergia gracilenta |
| Corolla lobes 6–12 mm long, 2–4 times as long as the tube; sepals triangular
Back to 6 | Wahlenbergia victoriensis |
| 8 | Corolla rotate, lobes more than 4 times as long as the tube; style strongly constricted near the stigmatic lobes | 9 |
| Corolla campanulate, lobes less than 4 times as long as the tube; style not constricted or constricted about halfway down
Back to 6 | 11 |
| 9 | Capsules elongated-obconic, more than twice as long as broad; corolla lobes 2–5 mm long, rarely to 9 mm | Wahlenbergia multicaulis |
| Capsules semiglobose or obconic, less than twice as long as broad; corolla lobes 3–14 mm long
Back to 8 | 10 |
| 10 | Plants typically few-stemmed; lower leaves obovate or oblanceolate; corolla lobes 5–14 mm long; eastern half of State | Wahlenbergia planiflora |
| Plants typically much-branched; lower leaves linear or oblanceolate; corolla lobes 3–9 mm long; chiefly on inland floodplains
Back to 9 | Wahlenbergia fluminalis |
| 11 | Lower leaves opposite, linear; capsules elongated-obconic, at least 3 times as long as broad | Wahlenbergia luteola |
| Lower leaves alternate or, if opposite, then broader than linear and capsules less than 3 times as long as broad
Back to 8 | 12 |
| 12 | Corolla lobes c. 3 times as long as the tube | 13 |
| Corolla lobes 1–2 times as long as the tube
Back to 11 | 15 |
| 13 | Lower leaves linear or narrow-oblanceolate; plants more or less glabrous (except for an hirsute form in SFWP); corolla lobes 5–9 mm long | Wahlenbergia littoricola |
| Lower leaves obovate or oblanceolate; plants glabrous to hirsute; corolla lobes 5–19 mm long
Back to 12 | 14 |
| 14 | Plants typically few-stemmed, hirsute towards the base; corolla lobes 6–19 mm long; widespread, tablelands to far-western plains | Wahlenbergia graniticola |
| Plants typically much-branched, glabrous or with scattered hairs; corolla lobes 5–8 mm long; confined to NFWP
Back to 13 | Wahlenbergia aridicola |
| 15 | Corolla tube 4–11 mm long, longer than the ovary; corolla lobes 6–20 mm long | 16 |
| Corolla tube 1–5 mm long, equal to or shorter than the ovary; corolla lobes 1.5–7 mm long
Back to 12 | 18 |
| 16 | At least the lowermost leaves opposite; sepals 3–16 mm long; capsules ellipsoid or globose | Wahlenbergia stricta |
| All leaves alternate, rarely the lowermost opposite; sepals 1–6 mm long; capsules obconic or semiglobose
Back to 15 | 17 |
| 17 | Capsules obconic or elongated-obconic, 4–9 mm long; lower leaves linear or oblanceolate; plants typically glabrous | Wahlenbergia communis |
| Capsules semiglobose or shortly obconic, 1.5–5 mm long; lower leaves oblanceolate or obovate; plants typically hirsute towards the base
Back to 16 | Wahlenbergia queenslandica |
| 18 | Perennials; capsules obconic; widespread, coast to western plains | Wahlenbergia gracilis |
| Annuals or perennials; capsules cylindric or globose, appearing swollen, especially in perennials; western plains and far western plains, growing in drier habitats than Wahlenbergia gracilis
Back to 15 | Wahlenbergia tumidifructa |
