Inflorescence axillary or terminal racemes or sometimes appearing solitary; flowers alternate. Sepals 4 [or 5], free or fused at base. Corolla with a short tube and 4 [or 5] spreading lobes; blue, lilac or pink, usually with darker veins. Stamens 2, exserted, epipetalous. Ovary 2-locular with a septum; style 1; ovules usually many; placentation axile or free-central.
Fruit a capsule, compressed or rarely 4-lobed or ± globose, usually emarginate, dehiscing by loculicidal splits and sometimes secondarily splitting septicidally.
| | Key to the species | |
| 1 | Annual or perennial herbs or semiwoody perennials;fruit capsule usually strongly laterally compressed, septicidal and often partly loculicidal | 2 |
| Woody perennials or subshrubs;fruit capsule usually not strongly compressed,septicidal and often partly loculicidal | 16 |
| 2 | Herbs growing in or near water; stems hollow, glabrous, mostly more than 30 cm high | 3 |
| Herbs of non-aquatic sites; stems not hollow, pilose, mostly less than 30 cm high
Back to 1 | 4 |
| 3 | Flowers blue or lilac, capsule usually slightly longer than broad and not or scarcely emarginate; fruiting pedicels ascending, mostly 5–6 mm long and longer than bracts | Veronica anagallis-aquatica |
| Flowers pink, capsule usually broader than long and slightly emarginate; fruiting pedicels spreading, mostly 2.5–3 mm long and shorter than bracts
Back to 2 | Veronica catenata |
| 4 | Perennial herbs, flowers in lateral racemes with bracts distinctly smaller than leaves | 5 |
| Annual or perennial herbs, flowers in axils of leaves or bracts on upper parts of leafy stems (ie. internal racemes); bracts similar to or much smaller than leaves
Back to 2 | 12 |
| 5 | Plant with above-ground stolons or prostrate stems | 6 |
| Plant with underground rhizomes
Back to 4 | 10 |
| 6 | Leaves mostly more than 30 mm long | 7 |
| Leaves mostly less than 30 mm long
Back to 5 | 8 |
| 7 | Leaves with base cuneate; capsules shallowly obcordate with rounded lobes; calyx lobes often glabrous toward apex; stem hairs mostly long and spreading | Veronica notabilis |
| Leaves with base mostly truncate; capsules slightly emarginate with somewhat diverging lobes; calyx lobes usually finely ciliate on margins and apex; stem hairs mostly short, slender and antrorsely curved
Back to 6 | Veronica grosseserrata |
| 8 | Leaves with rounded or subacute apex and teeth; hairs on stems 1–2 mm long | Veronica calycina |
| Leaves with acute apex and teeth; hairs on stems all or mostly less than 0.4 mm long
Back to 6 | 9 |
| 9 | Leaves with 3–8 teeth along each margin; very short stem hairs often mixed with longer hairs and not confined to lateral bands | Veronica plebeia |
| Leaves with 2–5 teeth along each margin; hairs on stems very short and inconspicuous, usually all less than 0.4 mm long, confined to lateral bands
Back to 8 | Veronica brownii |
| 10 | Calyx lobes in fruit elliptic to broad-obovate, 2.5–4 mm wide | Veronica sobolifera |
| Calyx lobes in fruit linear to narrow-obovate, 0.8–2.5 mm wide
Back to 5 | 11 |
| 11 | Stems with fine rigid hairs c. 0.5 mm long; leaves narrow-ovate or linear, mostly 1.5–4 mm wide, entire or with 1–4 pairs of spreading teeth; capsule broader than long, upper margin with scattered hairs | Veronica gracilis |
| Stems with very short hairs c. 0.1 mm long; leaves linear, mostly 0.6–2 mm wide, entire; capsule longer than broad, glabrous
Back to 10 | Veronica subtilis |
| 12 | Pedicels more than 5 mm long in fruit | 13 |
| Pedicels less than 5 mm long in fruit
Back to 4 | 14 |
| 13 | Pedicels 30–40 mm long in fruit; capsules distinctly broader than long | Veronica persica |
| Pedicels 12–18 mm long in fruit; capsules slightly broader than long
Back to 12 | Veronica hederifolia |
| 14 | Leaves ovate-triangular, coarsely toothed or crenate with obtuse teeth; bracts lanceolate or linear, acute | Veronica arvensis |
| Leaves narrow- or broad-elliptic, entire or finely toothed
Back to 12 | 15 |
| 15 | Leaves narrow-elliptic; style c. 0.2 mm long in fruit so that stigma appears sessile | Veronica peregrina |
| Leaves broad-elliptic, style 1.3–2.7 mm long in fruit
Back to 14 | Veronica serpyllifolia |
| 16 | Alpine prostrate sub-shrub usually less than 10 cm high with densely crowded leaves in 4 ranks: fruit slightly compressed laterally, obovate | Veronica densifolia |
| Not as above
Back to 1 | 17 |
| 17 | Leaves broad-ovate and toothed with the underside bright purple; found in the Central Tablelands | Veronica lithophila |
| Not as above
Back to 16 | 18 |
| 18 | Leaves linear or with linear lobes or divisions, not glaucous; capsules emarginate | 19 |
| Leaves very narrow-ovate to wide-ovate, green or glaucous; capsules acute or truncate or emarginate
Back to 17 | 20 |
| 19 | Leaves pinnately divided with the primary segments about a third to half as long as the leaves and often further divided or lobed; leaves usually in compact clusters on very short lateral branches at the lower nodes; capsules strongly compressed, 1–1.5 mm thick | Veronica nivea |
| Leaves entire or with teeth or lobes less than a fifth as long as the leaf; lateral branches not developing compact clusters of leaves; capsules compressed, 1.5–2 mm thick
Back to 18 | Veronica arenaria |
| 20 | Plant not conspicuously glaucous (except sometimes the lower surfaces of leaves); stems hairy with sparse or dense short hairs or glabrous; leaves with 15–80 teeth along each margin | 21 |
| Vegetative parts glabrous and glaucous; leaves entire or with up to 22 teeth along each margin
Back to 18 | 22 |
| 21 | Leaves glabrous or with only margins sparsely ciliate; hairs on stems usually denser in longitudinal bands, hairs 0.2–2 mm long; flowers white or pale lilac or pale blue | Veronica derwentiana |
| Leaves and stems densely and evenly covered with very short hairs 0.1–0.3 mm long; flowers violet-blue or pale lavender
Back to 20 | Veronica velutina |
| 22 | Leaves often V-shaped in cross section, recurved, with 6–18 teeth along each margin; capsules obtuse or truncate or emarginate | 23 |
| Leaves mostly flat and spreading, entire or toothed, with up to 10 or rarely more teeth along each margin; capsules acute or obtuse
Back to 20 | Veronica perfoliata |
| 23 | Corolla 6–7 mm long; capsules truncate or emarginate, 3–6.5 mm long | Veronica blakelyi |
| Corolla 9.5–11 mm long; capsules obtuse or truncate, mostly 6–9.5 mm long
Back to 22 | Veronica arcuata |
