Inflorescence racemose; bracteate, bracts basifixed or with an extension below the point of attachment (basisolute). Calyx 2- or rarely 4-lobed, usually free to the base but sometimes ± united. Corolla 2-lipped; upper lip usually smallest, with ± well-defined basal sac, apex entire, or ± 2-lobed (rarely more); lower lip often large, spurred.
Fruit a globose or ovoid capsule, usually dehiscing by longitudinal slits; seeds 1–many, usually small, variously shaped and winged, sometimes viviparous.
Treatment based on Taylor (1989). Definition of term: Basisolute (sometimes termed medifixed, spurred, peltate) = where a scale, bract or bracteole organ is attached at some point above its base.
| | Key to the species | |
| 1 | Bracteoles absent; flowers yellow (if not cleistogamous) or white to slightly reddish (cleistogamous) or blue | 2 |
| Bracteoles present; flowers white or shades of pink to violet, usually with a yellow palate | 7 |
| 2 | Inflorescence with a whorl of ellipsoid floats above middle | Utricularia stellaris |
| Inflorescence lacking floats
Back to 1 | 3 |
| 3 | Stolons anchored in substrate | 4 |
| Stolons freely suspended in water column
Back to 2 | 5 |
| 4 | Leaf lamina filiform, bi- or tri-pinnately divided; flowers blue | Utricularia biloba |
| Leaf lamina linear with subacute apex; corolla yellow (chasmogamous) or corolla reduced and white or reddish (cleistogamous)
Back to 3 | Utricularia subulata |
| 5 | Leaves with ultimate segments few (2–8); upper corolla lip larger than lower | Utricularia gibba |
| Leaves with ultimate segments numerous (20–80); upper corolla lip smaller than lower
Back to 3 | 6 |
| 6 | Corolla externally glabrous; peduncle with 1 or more scales; leaves with 2 primary segments | Utricularia australis |
| Corolla externally pubescent; peduncle lacking scales; leaves with 3 or more primary segments
Back to 5 | Utricularia aurea |
| 7 | Peduncle with scales present | 8 |
| Peduncle lacking scales
Back to 1 | 11 |
| 8 | Corolla with upper lip deeply and distinctly 2-lobed (like rabbit ears) | Utricularia sandersonii |
| Corolla with upper lip unlobed or shallowly 2-lobed
Back to 7 | 9 |
| 9 | Bracts basiolute (medifixed) | Utricularia caerulea |
| Bracts (inserted at base of flower pedicel) basifixed
Back to 8 | 10 |
| 10 | Bracts c. 4 times broader than bracteoles, c. 2 mm long, with apex acute | Utricularia uliginosa |
| Bracts mostly only slightly broader than bracteoles (up to twice width), c. 1 mm long, with apex subacute
Back to 9 | Utricularia lateriflora |
| 11 | Lower corolla lip with central yellow pair of ridges not projecting apically beyond ridges on either side | Utricularia uniflora |
| Lower corolla lip with central yellow pair of ridges projecting apically beyond ridges on either side
Back to 7 | 12 |
| 12 | Inflorescence 1–4 cm high, usually 1-flowered; corolla 6–10 mm long | Utricularia monanthos |
| Inflorescence 10–50 cm high, 2–many-flowered; corolla 12–22 mm long
Back to 11 | 13 |
| 13 | Lower corolla lip with 2 or 3 conspicuous yellow central ridges | Utricularia dichotoma |
| Lower corolla lip with 4–11 conspicuous yellow central ridges
Back to 12 | Utricularia beaugleholei |
