1. Ovary chamber 1
2. Hypanthium present
3. Sepals fused into conical cap that falls away as flower opens, 0 in open flower; petals 4 — funnel-shaped receptacle readily misinterpreted as a hypanthium ..... PAPAVERACEAE (Eschscholzia)
3' Sepals present in open flower; petals (2)5
4. Flowers ± radial; petals generally 5, oblanceolate to ± round, not recurved ..... ROSACEAE (2) {G10,15,21,23}
4' Flowers strongly bilateral; petals 2, narrowly awl-like, recurved — sepals obovate; fruit opening before seeds mature, becoming widely dehiscent ..... SAXIFRAGACEAE (Bensoniella)
2' Hypanthium 0
5. Inflorescence a spike or 1–many heads
6. Shrub or tree; fruit a legume ..... FABACEAE (Mimosoideae)
6' Herb; fruit a capsule, dehiscent at tip ..... RESEDACEAE (Reseda)
5' Inflorescence a cyme, raceme, panicle, or umbel, or flower solitary
7. Sepals 2–3 (fused into conical cap in Eschscholzia), early-deciduous, 0 in open flower; latex generally present [at least in roots], generally milky or colored ..... PAPAVERACEAE (Papaveroideae) {G12,15,20,24}
7' Sepals 2–5(8), persistent; milky or colored latex 0
8. Filaments fused at base into 3–5 bunches ..... HYPERICACEAE (2) {G24}
8' Filaments free to base
9. Sepals 3 or 5; placentas parietal, ovary chamber 1 (or ± 3–12 from intruded placentas); annual to shrub; plant hairy (± glabrous), not at all fleshy; capsule splitting by valves ..... CISTACEAE
9' Sepals 2–8; placentas free-central, ovary chamber 1; annual or taprooted perennial herb; plant ± glabrous, generally ± fleshy; capsule circumscissile or splitting by valves ..... MONTIACEAE {G19,24}
1' Ovary chambers 2–many
10. Leaves hollow, tubular, often holding watery fluid within ..... SARRACENIACEAE
10' Leaves with ordinary flat blades
11. Plant aquatic; leaves 1–4 dm, oblong or ovate to round, floating or rising a short distance above the water surface ..... NYMPHAEACEAE (Nuphar)
11' Plant terrestrial, sometimes in wet soil; leaves often < 1 dm
12. Flowers unisexual — ovary 3-lobed ..... EUPHORBIACEAE (Ditaxis) {G24}
12' Flowers bisexual
13. Filaments fused into tube around style; anther chamber 1 or appearing so
14. Flowers radial; stamens many; filament tube cylindric ..... MALVACEAE {G8,19,20}
14' Flowers bilateral; stamens 6–8; filament tube open on one side ..... POLYGALACEAE {G15,18,23,24}
13' Filaments free or fused at base into groups; anther chambers 2
15. Leaves opposite or whorled (distal occasionally alternate), entire
16. Petals yellow (salmon) ..... HYPERICACEAE (2) {G24}
16' Petals white to purple
17. Shrub — ovary actually 1/2 inferior but easily interpreted as superior ..... HYDRANGEACEAE (Carpenteria) {G16,21}
17' Herb ..... LYTHRACEAE {G24}
15' Leaves alternate throughout, entire to lobed
18. Hypanthium present ..... ROSACEAE (2) {G10,15,21,23}
18' Hypanthium 0
19. Petals 4–5; sepals 4–5, present in open flower, persistent in fruit; stamens 12–15 ..... NITRARIACEAE {G20}
19' Petals 6; sepals 3, early-deciduous, 0 in open flower; stamens many ..... PAPAVERACEAE (Romneya) {G12}
