1. Lvs opposite or whorled
2. Lvs 2-lobed, resin-coated; flowers bright yellow; fruit covered with white, spreading hairs — desert shrub; leaf sometimes treated as compound with 2 leaflets fused at base ..... ZYGOPHYLLACEAE (Larrea)
2' Lvs entire or toothed to palmately lobed or divided; flower ± green or white to creamy yellow, blue, or purple; fruit not covered with white, spreading hairs
3. Lvs lobed or divided; fruit splitting into mericarps
4. Shrub <= 1 m; stigmas 5, on long, stiff style; ovary not winged; mericarps wingless, each tipped by a spirally coiled beak ..... GERANIACEAE (Pelargonium) (2) {G24}
4' Tree or large shrub; stigmas 2(3), ± sessile; ovary 2(3)-winged; mericarps winged, beaks 0 ..... SAPINDACEAE (Acer) {G7,12}
3' Lvs entire or toothed; fruit a capsule or drupe
5. Lvs ± fleshy, salt encrusted, generally < 1 mm wide, united across node by a sheath ..... FRANKENIACEAE (Frankenia palmeri)
5' Lvs generally thin or leathery, not salt encrusted, generally >= 2 mm wide, not united by a sheath
6. Stamens = in number to petals
7. Stamens alternate petals; petals ± flat ..... CELASTRACEAE
7' Stamens opposite petals; petals generally ± cupped ..... RHAMNACEAE (2) {G12,21}
6' Stamens > in number than petals
8. Lvs ± whorled at some nodes, alternate at others, not gland-dotted ..... PITTOSPORACEAE (2) {G9}
8' Lvs all opposite or some in axillary clusters, gland-dotted ..... RUTACEAE (Cneoridium)
1' Lvs alternate, sometimes reduced to minute scales or so quickly deciduous that the plants are generally leafless
9. Lvs lobed
10. Tendrils present; plant a woody vine, generally trailing or climbing on other plants
11. Fls solitary, large and showy ..... PASSIFLORACEAE
11' Fls in panicles, small and inconspicuous ..... VITACEAE (Vitis) {G7,9,12}
10' Tendrils 0; plant ± erect, not climbing
12. Infl a panicle; flowers radial; 2–4 mm diam; fruit a drupe ..... ANACARDIACEAE (Rhus aromatica)
12' Infl an umbel; flowers ± bilateral, 15–40 mm wide; fruit splitting into 5 mericarps ..... GERANIACEAE (Pelargonium) (2) {G24}
9' Lvs entire or toothed, unlobed
13. Lf palmately veined, the blade well developed
14. Fls strongly bilateral ..... FABACEAE (Cercis)
14' Fls radial ..... RHAMNACEAE (Ceanothus)
13' Lf pinnately veined, 1-veined, or reduced to a bladeless scale
15. Fls strongly bilateral
16. Stamens 4, all inserted on 1 side of ovary, free or nearly so; sepals rose-purple, petal-like, widely spreading; upper 3 petals similar, stalked, free or fused, lower 2 petals reduced to fleshy scales or glands; fruit an indehiscent pod bearing slender, barb-tipped prickles ..... KRAMERIACEAE
16' Stamens 6–8 or 10, all filaments or 9 of 10 fused into a tube around the ovary [tube often open on 1 side]; sepals variously colored, sometimes petal-like; no petals reduced to fleshy scales or glands; fruit a capsule, legume, or unarmed, indehiscent pod
17. Sepals all fused, at least at base, forming a cup-shaped to cylindric calyx tube, generally not petal-like; the odd petal [banner] uppermost, overlapping the margins of the 2 upper lateral petals; lower 2 lateral petals generally free at base but fused toward the tip, forming a keel that encloses stamens and ovary; fruit a legume or indehiscent pod ..... FABACEAE (Papilionoideae)
17' Sepals free, petal-like, 2 of them spreading and very different from the other 3; the odd petal lowermost, often appendaged, folded and forming a keel enclosing stamens and ovary, a banner petal never present; fruit a flattened capsule ..... POLYGALACEAE {G15,18,22,24}
15' Fls radial or nearly so
18. Stamens > in number than petals (sterile stamens as many as petals in pistillate flowers of Castela (Simaroubaceae))
19. Petals dark blue-purple; stems and leaves gland-dotted, very strongly scented ..... RUTACEAE (Thamnosma)
19' Petals white to yellow or green; stems and leaves not scented
20. Hypanthium present, well developed, tubular or cup-shaped ..... ROSACEAE {G10,15,20,21,22}
20' Hypanthium 0 or small and disk-shaped
21. Anthers opening by small round pores; petals 5; stem not thorn-tipped; moist sites ..... ERICACEAE (Rhododendron columbianum)
21' Anthers opening along sides by long slits; petals 4–6; stems (except Glossopetalon pungens) generally thorn-tipped; arid sites
22. Fls unisexual; ovary deeply 4–8-lobed ..... SIMAROUBACEAE (Castela) {G7,9,10}
22' Fls bisexual; ovary unlobed
23. Petals generally 5; ovary sessile on receptacle, chamber 1; stem angled; leaves oblong or narrowly elliptic to obovate, deciduous or ± persistent; fruit a follicle ..... CROSSOSOMATACEAE (Glossopetalon) (2)
23' Petals 4; ovary raised ± 1 mm above receptacle on short stalk, chambers 2; stem smooth; leaves scale-like, soon deciduous; fruit a berry ..... KOEBERLINIACEAE
18' Stamens = in number to petals
24. Lvs all reduced to bladeless scales; twigs very slender, jointed, green ..... TAMARICACEAE
24' Lvs with expanded blades, linear to (ob)ovate, sometimes early deciduous; twigs not jointed, green or brown
25. Stamens opposite petals; petals generally with cupped blade ..... RHAMNACEAE (2) {G12,21}
25' Stamens alternate petals; petals generally flat
26. Lvs 6–17 mm
27. Fls many in tight, leafy-bracted panicle; ovary chambers 5 ..... CELASTRACEAE (Mortonia)
27' Fls solitary, axillary; ovary chamber 1 ..... CROSSOSOMATACEAE (Glossopetalon) (2)
26' Lvs 15–150 mm
28. Petals 8–15 mm ..... PITTOSPORACEAE (2) {G9}
28' Petals 1.5–3 mm
29. Lvs 20–80 mm wide, elliptic to ovate; flowers many in terminal panicle ..... ANACARDIACEAE {G7,9,20}
29' Lvs 5–10 mm wide, ± lanceolate; flowers 1–few, axillary ..... CELASTRACEAE (Maytenus)
