1. Stamens > 2 × as many as petals or > 15
2. Style 1
3. St fleshy, spiny (in some Opuntia species only with glochids); sepals and petals indefinite in number and not sharply differentiated, in spirals ..... CACTACEAE {G17}
3' St not fleshy, generally not spiny; sepals and petals each 3–7, clearly differentiated, in whorls
4. Herb or subshrub with rough, barbed, or stinging hairs ..... LOASACEAE
4' Tree or shrub lacking such hairs
5. Ovary only 1/2 inferior, the free portion conic, especially in fruit ..... HYDRANGEACEAE (Carpenteria) {G22}
5' Ovary ± wholly inferior, the free portion, if any, rounded
6. Lf generally dotted with embedded oil glands, often strongly scented when crushed; ovary chambers generally 2–5, all at 1 level; flowers variously colored ..... MYRTACEAE
6' Lf not gland-dotted, not strongly scented; ovary chambers generally 5 or more, some at different levels in the ovary; flowers bright red-orange to pale yellow ..... LYTHRACEAE (Punica)
2' Styles or sessile stigmas > 1, sometimes partly fused at base
7. Shrub or tree, woody throughout, not fleshy; petals generally 4–5
8. Lvs opposite; fruit a capsule ..... HYDRANGEACEAE (Philadelphus)
8' Lvs alternate; fruit a pome ..... ROSACEAE (2) {G10,15,20,22,23}
7' Herb or plant woody only at base, generally ± fleshy; petals 4–many
9. Plant aquatic; leaf blades and flowers floating at water surface ..... NYMPHAEACEAE (Nymphaea)
9' Plant terrestrial; leaves and flowers not floating
10. Sepals 4–8; petals many ..... AIZOACEAE {G14,15,17}
10' Sepals 2; petals 5 ..... PORTULACACEAE (2)
1' Stamens 2 × as many as petals or fewer
11. Stamens opposite and = in number to petals
12. Shrub or tree ..... RHAMNACEAE {G12,23}
12' Herb — petals actually slightly fused at base, easily misinterpreted as free ..... THEOPHRASTACEAE {G17}
11' Stamens alternate petals or different in number
13. Style 1, sometimes distally branched
14. Plant a tendril-bearing vine; flowers unisexual, plant monoecious — corolla sometimes so deeply divided that petals appear to be free ..... CUCURBITACEAE {G6,8,14,17}
14' Plant not tendril-bearing; flowers generally bisexual
15. Ovules > 1 per chamber
16. Herb (subshrub) ..... ONAGRACEAE {G5}
16' Shrub
17. Stamens 5, free; leaves ovate or obovate to round, generally palmately 3–5-lobed, generally toothed; glands stalked or 0 ..... GROSSULARIACEAE (2)
17' Stamens 10, fused in ring with staminodes; leaves linear needle-like, entire, opposite; glands embedded in leaves ..... MYRTACEAE ([Chamelaucium])
15' Ovule 1 per chamber or perennial herb ovary
18. Lvs alternate
19. Plant a non-desert, sprawling, woody vine (flower stems ± erect); leaves smooth, dark green, often palmately lobed; inflorescence a cluster of umbels; fruit a berry ..... ARALIACEAE (Hedera)
19' Plant a low-desert per; leaves generally scabrous, pale green, unlobed; inflorescence ± a raceme; fruit an achene ..... LOASACEAE (Petalonyx)
18' Lvs opposite; sepals and petals 4(5)
20. Perennial to tree; inflorescence an umbel, head, or cyme; fruit a drupe ..... CORNACEAE
20' Annual; inflorescence a spike or spike-like raceme; fruit indehiscent, nut-like ..... ONAGRACEAE (Clarkia heterandra)
13' Styles > 1
21. Seeds 1–2 per chamber
22. Infls of umbels or heads (spike in Hydrocotyle verticillata)
23. Lvs various [if round-reniform, plant terrestrial], glabrous or hairy; inflorescence generally compound umbel (occasionally simple umbel, head) ..... APIACEAE {G2,6,8,14,20}
23' Lvs round-peltate or -reniform, glabrous; plant aquatic with stolons or rhizomes, floating or rooted in shallow water or on mud; inflorescence simple umbel or spike ..... ARALIACEAE (Hydrocotyle) {G2,14}
22' Infls various but not of umbels, heads, or spikes
24. Lvs alternate; hypanthium well developed; fruit a pome ..... ROSACEAE (2) {G10,15,20,22,23}
24' Lvs opposite; hypanthium very short or 0; fruit a capsule ..... HYDRANGEACEAE {G24}
21' Seeds generally several–many per chamber
25. Sepals 2; leaves fleshy ..... PORTULACACEAE (2)
25' Sepals 4–5; leaves generally not fleshy
26. Herb ..... SAXIFRAGACEAE {G10,20,24}
26' Shrub
27. Stamens 4–5 ..... GROSSULARIACEAE (2)
27' Stamens 10 ..... HYDRANGEACEAE (Jamesia)
