Inflorescences spikes, heads or rarely flowers solitary. Flowers bisexual, in axils of sepaloid bracts. Sepals ± membranous, with a ± prominent keel; persistent in fruit. Corolla scarious or membranous, narrowly tubular, 4-lobed. Placentation axile, ovules mostly 1–6 in each loculus.
The introduced species include several widespread weeds and commonly colonize disturbed sites, but most of the native species are characteristically in relatively undisturbed habitats. P. hedleyi Maiden is endemic to Lord Howe Is.
| | Key to the species | |
| 1 | Spikes mostly with 1–9 flowers | 2 |
| Spikes with more than 10 flowers | 4 |
| 2 | Leaves mostly less than 5 mm wide; scapes elongated at flowering stage with flowers held above leaf bases, rosettes small forming a turf | Plantago glacialis |
| Leaves more than 5 mm wide; scapes very short at flowering stage so that flowers are among the leaf bases (scapes elongating after flowering); rosettes larger (mostly 5–10 cm diam.) not forming a turf
Back to 1 | 3 |
| 3 | Leaves glossy, usually spreading; upper bracts broad-elliptic and thick | Plantago muelleri |
| Leaves dull, usually more or less erect; upper bracts narrow-elliptic, thickened only on the keel
Back to 2 | Plantago palustris |
| 4 | Plants either with elongated branching leafy stems, or with leaves mostly pinnately lobed | 5 |
| Stems not elongated and branching; leaves entire or toothed
Back to 1 | 6 |
| 5 | Leaves entire, on elongated branching stems | Plantago arenaria |
| Leaves mostly deeply pinnately or bipinnately lobed, all basal
Back to 4 | Plantago coronopus |
| 6 | Corolla lobes erect and rigid after flowering; ovules 3 | Plantago myosuros |
| Corolla lobes spreading and not rigid after flowering; ovules more than 3
Back to 4 | 7 |
| 7 | Ovules and seeds 8–16; leaves with lamina ovate or broad- elliptic, petiole about as long as the lamina | Plantago major |
| Ovules 4 or 5, seeds 1–5, leaves either with lamina narrower or petiole shorter than the lamina
Back to 6 | 8 |
| 8 | Taproot not developed | 9 |
| Taproot developed
Back to 7 | 11 |
| 9 | Leaves thin-textured, more than 3 times as long as broad | Plantago cladarophylla |
| Leaves fleshy or leathery, less than 3 times as long as broad
Back to 8 | 10 |
| 10 | Leaves mostly 3-veined, lateral veins much less conspicuous on upper surface than midvein and not extending into upper half of lamina; fruiting spikes usually 0.8–4 cm long | Plantago alpestris |
| Leaves usually at least 5-veined, veins mostly all conspicuous on upper surface and all extending into upper half of lamina; fruiting spikes usually 4–8 cm long
Back to 9 | Plantago euryphylla |
| 11 | Scapes with regular longitudinal ridges; anterior sepals fused into a 2-lobed structure with 2 veins | Plantago lanceolata |
| Scapes not conspicuously ridged; sepals all free
Back to 8 | 12 |
| 12 | Annuals; capsules large, either 3.4–5 mm long, or with a truncate beak, or distinctly contracted below apex | 13 |
| Perennials; capsules not as above
Back to 11 | 16 |
| 13 | Capsules with an almost cylindrical beak, the apex truncate and minutely lobed | Plantago turrifera |
| Capsules acute or apex rounded, without a cylindrical beak
Back to 12 | 14 |
| 14 | Capsules large, 2.2–3.2 mm diam., not distinctly contracted below apex; bracts and sepals usually dark brown or blackish | 15 |
| Capsules smaller, usually 1.7–2.0 mm diam., distinctly contracted below apex; bracts and sepals pale or dark brown
Back to 13 | Plantago cunninghamii |
| 15 | Leaves 3–24 mm wide; capsules acute | Plantago drummondii |
| Leaves 0.7–2 mm wide; capsules rounded
Back to 14 | Plantago multiscapa |
| 16 | Sepals with a glabrous keel or with a few hairs only | 17 |
| Sepals with a pilose keel
Back to 12 | 19 |
| 17 | Sepals mostly 1.5–2.0 mm long; leaves thin-textured | 18 |
| Sepals mostly 2.1–2.5 mm long; leaves thick-textured
Back to 16 | Plantago antarctica |
| 18 | Leaves linear-elliptic to lanceolate; sepals with a rounded or flattened keel; capsules 2.5–3.8 mm long | Plantago cladarophylla |
| Leaves oblanceolate to obovate; sepals usually sharply keeled; capsules 1.7–3.0 mm long
Back to 17 | Plantago debilis |
| 19 | Sepals mostly 2.8–3.5 mm long; axils of leaves with tufts of red-brown or deep golden-brown hairs 2–6 mm long | 20 |
| Sepals 1.5–2.8 mm long (rarely to 3 mm); axils of leaves with short whitish or yellowish brown hairs
Back to 16 | 21 |
| 20 | Leaves narrow-elliptic to oblong-oblanceolate, 5–10 times as long as broad, pilose with soft short hairs to 1 mm long | Plantago varia |
| Leaves linear or very narrow-elliptic, more than 15 times as long as broad, either glabrous or pilose with long or short hairs
Back to 19 | Plantago gaudichaudii |
| 21 | Sepals mostly 1.5–2.2 mm long; leaves mostly oblanceolate to obovate, rarely narrower, 8–40 mm wide; spikes usually lax at maturity | Plantago debilis |
| Sepals mostly 2.2–2.8 mm long; leaves mostly narrow-oblong to oblanceolate, 3–21 mm wide; spikes usually compact at maturity
Back to 19 | Plantago hispida |
