| | 1. Corolla 8–17 mm, limb 6–10 mm wide; calyx 5–9.5 mm |
| |
| | 2. Leaves 3–5-lobed; calyx hairs spreading |
| V. gooddingii |
| | 2' Leaves 1–2-pinnately dissected; calyx hairs appressed |
| V. tenuisecta |
| | 1' Corolla 1.5–6 mm, limb < 5 mm wide; calyx 2.5–4 mm |
| |
| | 3. Flower bract 4–8 mm, 2–3 mm > calyx; most stems prostrate to decumbent |
| V. bracteata |
| | 3' Flower bract 1–4.5 mm, generally < calyx; most stems ascending to erect |
| |
| | 4. Most cauline leaf blades 1–2-lobed (lobes below middle 8–25 mm deep), toothed |
| |
| | 5. Herbage sparsely strigose; calyx minutely strigose |
| V. menthifolia |
| | 5' Herbage and calyx short-spreading-(generally soft-)hairy |
| 2 V. lasiostachys |
| | 6. Leaf surface grayish green above, hairs generally soft; nutlet scar brownish at 20× |
| var. lasiostachys |
| | 6' Leaf surface green above, hairs generally stiff; nutlet scar white-papillate at 20× |
| var. scabrida |
| | 4' Most cauline leaf blades generally unlobed (except some V. hastata), teeth 2–8 mm |
| |
| | 7. Lower and mid-cauline petioles generally 1–2.5 cm, sometimes narrowly winged |
| |
| | 8. Petioles, inflorescence axis, and calyx short-spreading-(generally soft-) hairy |
| 2 V. lasiostachys (see 6. for vars.) |
| | 8' Petioles, inflorescence axis, and calyx strigose or scabrous |
| |
| | 9. Fruits generally overlapping (axis with 8–10 fruits per cm); upper surface of leaves rough-puberulent to slightly scabrous |
| V. hastata |
| | 9' Fruits not overlapping, especially below (axis generally with < 8 fruits per cm); upper surface of leaves strigose to scabrous |
| V. scabra |
| | 7' Lower and mid-cauline petiole generally 0 (blade often clasping) |
| |
| | 10. Fruits not overlapping (especially below middle); flower bracts 3.5–4 mm; calyx 4–4.5 mm; spikes 1–5 per cluster |
| V. californica |
| | 10' Fruits overlapping; flower bracts 3–3.5 mm; calyx 3–3.5 mm; spikes generally 5–17 per cluster |
| |
| | 11. Leaf base cordate to truncate, generally clasping; spikes ± 5–6 mm diam in fruit |
| V. bonariensis |
| | 11' Leaf base ± acute, subsessile; spikes 3–4 mm diam in fruit |
| V. litoralis
|