1. Fl bilateral
2. Proximal part of calyx with a protruding, hollow spur
3. Lf not peltate; ovary chambers 5, several-seeded; fruit an exploding capsule ..... BALSAMINACEAE {G16}
3' Lf peltate; ovary chambers 3, 1-seeded; fruit breaking into 3 1-seeded mericarps ..... TROPAEOLACEAE
2' Proximal part of calyx without a protruding spur, spur 0 or fused to pedicel
4. Filaments of all or all but 1 stamen fused, at least proximally
5. Petals not strongly overlapping; ovary chambers and style branches 5; style base elongating, forming a stiff beak, beak segments coiled on segments of dry fruit ..... GERANIACEAE (Pelargonium) {G23}
5' Petals strongly overlapping; ovary chambers 1 or 2, style unbranched, not forming beak on fruit
6. 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)
6' Sepals free, 2 of them petal-like, 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 {G15,18,22,23}
4' Filaments free (0 or fused in pairs)
7. Fls solitary; petals 5 ..... VIOLACEAE {G5,15,20}
7' Fls in raceme or spike; petals 2 or 4
8. Infl a spike; ovary 4-lobed, stigmas 4; developing fruit open at tip; stamens 3–4 ..... RESEDACEAE (Oligomeris)
8' Infl a raceme or panicle; ovary unlobed or 2-lobed, stigma 1–2; developing fruit closed at tip
9. Sepals free to base; stamens 6; flowers not subtended by bracts ..... BRASSICACEAE (2) {G2,15,20}
9' Sepals proximally fused to hypanthium; stamens 3; each flower subtended by a bract ..... SAXIFRAGACEAE (Tolmiea)
1' Fl radial
10. Plants without green pigmentation ..... ERICACEAE (2) {G17,18,19}
10' Plants green and photosynthetic
11. Petals 4
12. Lvs alternate, sometimes all basal
13. Lvs ± fleshy; sepals 2 ..... MONTIACEAE (Calyptridium) {G16}
13' Lvs not fleshy; sepals 4 ..... BRASSICACEAE (2) {G2,15,20}
12' Lvs opposite or whorled
14. Lvs ± cylindric or 3-angled in ×-section, fleshy; flowers unisexual, dioecious per or subshrub; petals present only in staminate flowers ..... BATACEAE {G6,8,15}
14' Lvs not fleshy; flowers bisexual, annual to subshrub; petals present in all flowers
15. Sepals free or nearly so, hypanthium 0
16. Petals 6–20 mm, each bearing a prominent, fringed appendage ..... GENTIANACEAE
16' Petals <= 6 mm, not appendaged
17. Fls pedicelled, terminal or from distal axils, sometimes in cymes; leaf without stipules; stamens 4 or 8 ..... CARYOPHYLLACEAE (4) {G6,8,15}
17' Fls ± sessile in leaf axils (pedicel elongating in fruit); leaf with stipules; stamens 8 ..... ELATINACEAE (Elatine californica)
15' Sepals fused, at least toward base, or hypanthium present
18. Lvs generally shallowly few-toothed; inflorescence a dense cyme or raceme borne on a terminal peduncle — ovary actually 1/2 inferior but easily misinterpreted as superior ..... HYDRANGEACEAE {G21}
18' Lvs entire; inflorescence of axillary or terminal cymes or flowers solitary, axillary
19. Petals borne on receptacle; style 2–3(4)-branched, rarely unbranched ..... FRANKENIACEAE (2)
19' Petals borne on inner face of hypanthium; style unbranched ..... LYTHRACEAE {G22}
11' Petals 5 or more
20. Fl unisexual ..... EUPHORBIACEAE (Ditaxis) {G22}
20' Fl bisexual
21. Sepals 2 or 3
22. Lvs ± fleshy; sepals persistent on opened flower and fruit ..... MONTIACEAE {G19,22}
22' Lvs not fleshy; sepals early-deciduous, 0 in open flower and fruit ..... PAPAVERACEAE {G15,20,22}
21' Sepals 5 or more
23. Stamens > in number than petals
24. Lvs alternate, sometimes all basal
25. Style branches and stigmas 5; style elongating, forming a beak; ovules 1 per ovary chamber; fruit breaking into 5 one-seeded mericarps, each tipped with a coiled beak segment ..... GERANIACEAE (Geranium) {G20}
25' Styles or style branches 1–3, stigmas 1–3; style not elongating or forming a beak; ovules several–many per ovary chamber; fruit a capsule
26. Stigmas 2–3, sessile or borne on 2–3 styles or style branches ..... SAXIFRAGACEAE (2) {G10,20,21}
26' Stigma 1, sessile or borne on an unbranched style
27. Fl disk-shaped, without a hypanthium; stamens dehiscent by pores ..... ERICACEAE (2) {G17,18,19}
27' Fl with a tubular hypanthium; stamens dehiscent along the sides by slits ..... LYTHRACEAE (Lythrum) (2)
24' Lvs opposite or whorled
28. Stigma and style 1
29. Fl without a hypanthium; leaf toothed ..... ERICACEAE (Chimaphila)
29' Fl with a tubular hypanthium; leaf entire ..... LYTHRACEAE (Lythrum) (2)
28' Stigmas 2–6
30. Lf lobed; opposite leaves a single pair, the remainder all basal; stigmas 3 — ovary chamber 1, placentas parietal — ovary actually ± 1/2 inferior ..... SAXIFRAGACEAE (Lithophragma cymbalaria)
30' Lf entire or shallowly toothed; opposite leaves generally several–many pairs; stigmas 2–6
31. Lf entire; ovary chamber 1 (rarely 2–4)
32. Lf not gland-dotted; petals white to pink, purple, or red; placentas free-central (axile) ..... CARYOPHYLLACEAE (4) {G6,8,15}
32' Lf gland-dotted; petals yellow; placentas parietal ..... HYPERICACEAE {G22}
31' Lf crenate-serrate to serrate; ovary chambers 5–6
33. Fls 1–few, sessile or short-pedicelled in leaf axils; annual; leaf teeth gland-tipped ..... ELATINACEAE (Bergia)
33' Fls in a dense cyme or raceme borne on a terminal peduncle; perennial herbs to subshrub; leaf teeth not gland-tipped — ovary actually 1/2 inferior but easily misinterpreted as superior ..... HYDRANGEACEAE (Whipplea)
23' Stamens = in number to petals or fewer
34. Lvs opposite or whorled
35. Lvs, or at least distal-most, toothed or lobed (proximally generally entire in Sclerolinon)
36. Petals white to pink or purple; inflorescence an umbel ..... GERANIACEAE (2)
36' Petals yellow; inflorescence a cyme ..... LINACEAE (Sclerolinon)
35' Lvs entire
37. Stamens opposite petals — petals actually fused but easily misinterpreted as free ..... MYRSINACEAE {G19}
37' Stamens alternate petals or of different numbers
38. Sepals evidently fused above base
39. Lf ± linear, acute ..... CARYOPHYLLACEAE (4) {G6,8,15}
39' Lf oblong to obovate, obtuse, margin often curled under and leaf appearing narrower ..... FRANKENIACEAE (2)
38' Sepals free or nearly so
40. Petals without fringed nectary pits ..... CARYOPHYLLACEAE (4) {G6,8,15}
40' Base or center of each petal with 2 fringed nectary pits (sometimes appearing as 1 due to overlapping fringes) — petals actually fused but easily misinterpreted as free ..... GENTIANACEAE (Swertia)
34' Lvs alternate, sometimes all basal
41. Lf linear, entire
42. Lvs cauline; flowers solitary or in racemes, panicles, or cymes ..... LINACEAE (2)
42' Lvs all basal; flowers in scapose heads ..... PLUMBAGINACEAE (Armeria)
41' Lf wider, often toothed or lobed
43. Lf covered with long, gland-tipped, insect-trapping hairs ..... DROSERACEAE
43' Lf without insect-trapping hairs
44. Styles, style branches, or stigmas 2–4
45. Fls solitary; stamens alternating with toothed or fringed staminodes; stigmas 4 ..... PARNASSIACEAE
45' Fls 2–many; staminodes 0; stigmas 2–3
46. Annual; leaf veins pinnate or lateral veins obscure; hypanthium 0; ovary unlobed ..... LINACEAE (2)
46' Perennial; leaf veins ± palmate; hypanthium present; ovary generally 2–3-lobed distally ..... SAXIFRAGACEAE (2) {G10,20,21}
44' Styles or style branches 5 or more
47. Filaments fused in tube around style; petals thread-like ..... MALVACEAE (Ayenia)
47' Filaments free or fused only at base; petals wider
48. Style elongating, forming a beak; fruit breaking into 5 one-seeded mericarps, each tipped with a coiled beak segment; flowers in umbels ..... GERANIACEAE (2)
48' Styles not elongating and forming a beak; fruit not breaking into mericarps; flowers in a raceme, cyme, or panicle-like inflorescence
49. Sepals free, ± green; fruit a capsule, 5- or 10-seeded; flowers in a raceme or cyme ..... LINACEAE (Linum)
49' Sepals fused, generally pink to blue; fruit indehiscent, 1-seeded; flowers in a panicle-like inflorescence ..... PLUMBAGINACEAE (Limonium)
