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Key to families | Table of families and genera




Martin F. Wojciechowski, except as noted


Key to Fabaceae

Key to Groups

1. Flower radial; calyx, corolla generally inconspicuous; petals free or fused, lobes not overlapped in bud; stamens 10 or generally many, often long-exserted; leaf 2-pinnate (simple in alien Acacia) ..... Group 1: Mimosoideae

1' Flower generally bilateral, less often ± radial; calyx, corolla generally conspicuous; petals overlapped in bud, free or 2 lowermost ± fused; stamens 10 (or 5, 6, 7, 9), generally ± included; leaf 1- or 2-pinnate (less often simple or palmately compound)

2. Flower ± radial to ± bilateral; sepals fused only at very base; leaf 1- or 2-pinnate ..... Group 2: Caesalpinioideae (except Cercis)

2' Flower bilateral; sepals free to ± entirely fused; leaf simple, 1-pinnate, or palmate

3. Upper petal (banner) inside lateral ones (wings) in bud; stamens free; leaf simple, reniform or bi-lobed ..... Group 2: Caesalpinioideae (Cercis only)

3' Upper petal (banner) outside lateral ones (wings) in bud (only banner present in Amorpha, petal position not evident in some Dalea); stamens generally with all or 9 filaments fused (free in Thermopsis, Pickeringia, Calia); leaf 1-pinnate (leaflets often 3), some palmately compound (especially Lupinus) or simple ..... Group 3: Papilionoideae

Group 1: Mimosoideae

1. Stamens 10; 1° leaflets generally 2–4 ..... PROSOPIS

1' Stamens > 10; 1° leaflets generally > 4, or leaf simple

2. Filaments fused below, free above; leaf 2-pinnate

3. Inflorescence axillary spike-like racemes or ± terminal panicle of head-like racemes; petiole with a gland; fruit not or slowly dehiscent, valves not recurving; Sacramento Valley, Central Coast, San Francisco Bay Area, Outer South Coast Ranges, Southwestern California ..... ALBIZIA

3' Inflorescence axillary heads; petiole without a gland; fruit dehiscent, valves recurving; Sonoran Desert ..... CALLIANDRA

2' Filaments free; leaf 2-pinnate or simple

4. Plant unarmed ..... ACACIA (2)

4' Plant armed with prickles or stipular spines

5. Plant armed with prickles ..... SENEGALIA

5' Plant armed with stipular spines

6. Leaf simple ..... ACACIA (2)

6' Leaf 2-pinnate ..... VACHELLIA

Group 2: Caesalpinioideae

1. Leaf simple; corolla pink-purple ..... CERCIS

1' Leaf compound; corolla generally ± yellow

2. Leaf 1-pinnate, plant unarmed or main leaf axis generally > 2 cm, a weak spine at tip; corolla generally yellow ..... SENNA

2' Leaf generally 2-pinnate (both 1- and 2-pinnate in some), plant armed, main leaf axis generally < 2 cm (except Gleditsia), a strong spine at tip, or (if leaf interpreted as 1-pinnate; see Parkinsonia), leaf subtended by a strong spine generally < 2 cm and main leaf axis not a spine at tip; corolla ± yellow to orange, less often ± red or with orange to ± red marks

3. Flower ± 3–5 mm; sepals, petals ± alike in color, texture; plant tree, generally armed ..... GLEDITSIA

3' Flower > 5 mm; sepals, petals not alike in color, texture; plant perennial herb, shrub, small tree, armed or not

4. Plant unarmed

5. Shrub, small tree, < 4 m; 2° leaflets 14–22 ..... CAESALPINIA (2)

5' Perennial herb, shrub, < 30 cm or < 2.5 m; 2° leaflets 3–13 ..... HOFFMANNSEGGIA

4' Plant armed

6. Plant with scattered prickles; sepals not alike; fruit indehiscent ..... CAESALPINIA (2)

6' Plant with stipular spines at nodes or thorns in leaf axils (see leaf scars) or main leaf axis a strong spine; sepals alike; fruit indehiscent to partly dehiscent late ..... PARKINSONIA

Group 3: Papilionoideae

1. Shrub to tree

2. Plant generally armed with prickles, spines, or thorns

3. Leaves simple, sometimes small or falling early

4. Plant gland-dotted; corolla indigo blue to pink-purple; seed 1 ..... PSOROTHAMNUS (4)

4' Plant not gland-dotted; corolla yellow to ± red; seeds (1)2–several

5. Corolla red-purple; fruit narrowed between seeds, glabrous ..... ALHAGI

5' Corolla yellow; fruit not narrowed between seeds, densely hairy ..... ULEX

3' Leaves all or mostly compound, generally persistent

6. Leaf simple or palmately compound; all filaments free ..... PICKERINGIA

6' Leaf pinnately compound; all or 9 filaments fused

7. Plant gland-dotted; fruit indehiscent; seed 1 ..... PSOROTHAMNUS (4)

7' Plant not gland-dotted; fruit dehiscent (sometimes slowly so); seeds generally several

8. Leaf even-pinnate; corolla wings purple-pink suffused with white, banner, keel yellow-white to pink or purple; fruit not flat, generally narrowed between seeds ..... OLNEYA

8' Leaf odd-pinnate; corolla white or pink; fruit flat, not narrowed between seeds ..... ROBINIA (2)

2' Plant unarmed

9. Petal 1 (the banner) — inflorescence spike-like; fruit indehiscent; seed 1 ..... AMORPHA

9' Petals 5

10. Filaments all fused; leaves simple or ternately or palmately compound

11. Leaves simple, < 2.5 cm; stems generally ± leafless ..... SPARTIUM

11' Leaves simple or generally compound, generally > 2.5 cm; stems leafy

12. Leaf of 3–17 leaflets, palmately compound; corolla blue, purple, white, or yellow, banner glabrous to densely hairy, keel generally beaked ..... LUPINUS (2)

12' Leaf of 1–3 leaflets, appearing simple or not; corolla yellow or white, banner generally glabrous, keel obtuse

13. Style generally abruptly curved at ± middle or gently curved ± throughout; upper lip of calyx ± 2-lobed ..... CYTISUS

13' Style ± abruptly bent at tip; upper lip of calyx 2-lobed ..... GENISTA

10' Filaments all free or 9 fused, 1 (uppermost) free or 0; leaves generally odd-pinnately compound (or leaflet number, arrangement generally irregular, as sometimes in Acmispon)

14. Inflorescence generally an umbel or flowers 1–2; corolla generally yellow ..... ACMISPON (3)

14' Inflorescence a raceme; corolla yellow or not

15. Corolla yellow with dark marks; fruit papery, inflated ..... COLUTEA

15' Corolla white or pink to purple; fruit not papery, not inflated

16. Flower 6–10 mm; plant gland-dotted; fruit indehiscent; seed 1 (see also Marina) ..... PSOROTHAMNUS (4)

16' Flower 14–25 mm; plant not gland-dotted; fruit dehiscent or not; seeds several

17. Fruit dehiscent, flat, not narrowed between seeds; filaments 9 fused, 1 free; corolla ± white to pink ..... ROBINIA (2)

17' Fruit indehiscent, not flat, ± narrowed between seeds; filaments all free; corolla ± blue-purple ..... [Calia secundiflora]

1' Annual, biennial, perennial herb, vine, subshrub

18. Leaflets 0, but stipules leaflet-like — leaf axis ending as a tendril ..... [Lathyrus aphaca]

18' Leaflets 2–many

19. Leaf palmately compound, leaflets generally 3–9

20. All filaments free; corolla yellow, 15–25 mm ..... THERMOPSIS

20' All or 9 filaments fused; corolla not yellow or, if so, generally < 15 mm

21. Leaflets gland-dotted; fruit indehiscent or transversely dehiscent; seed 1

22. Leaves ± basal or clustered near stem tips; leaflets elliptic to oblanceolate or widely obovate; fruit included in calyx except for beak ..... PEDIOMELUM

22' Leaves cauline; leaflets obovate to linear; fruit exserted from calyx ..... LADEANIA

21' Leaflets not gland-dotted; fruit indehiscent or dehiscent through longitudinal sutures; seeds generally several

23. Filaments of all stamens fused; leaflets generally 5–9, entire ..... LUPINUS (2)

23' Filaments of 9 stamens fused, the 10th (uppermost) free; leaflets 3–5, entire, toothed, or wavy

24. Leaflets 3–9, lower 2 in stipular position or not, others ± palmately arranged, stipules gland-like, reduced to bumps, or inconspicuous, inflorescence an umbel or 1–3-flowered, corolla generally yellow (see also Acmispon) ..... LOTUS

24' Leaflets generally 3, lower 2 not in stipular position, stipules generally papery or membranous, not reduced to bumps, not inconspicuous, rarely leaflet-like, if so then inflorescence not an umbel and corolla not yellow

25. Leaflet entire; fruit not enclosed in corolla ..... ASTRAGALUS (3)

25' Leaflet ± toothed or wavy; fruit generally enclosed in corolla ..... TRIFOLIUM (2)

19' Leaf pinnately to subpalmately compound (axis apparent beyond lowermost leaflets), leaflets 2–many

26. Leaflets 2; main leaf axis ending as tendril or bristle ..... LATHYRUS (2)

26' Leaflets >= 3; main leaf axis ending as leaflet, tendril, or bristle

27. Leaflets 3; fruit generally indehiscent (generally dehiscent in Phaseolus)

28. Keel petals spirally coiled; leaflet generally lobed — trailing or twining vine ..... PHASEOLUS

28' Keel petals not spirally coiled; leaflet entire, toothed, or wavy

29. Leaflet toothed or wavy — fruit ovate or reniform, generally 1-seeded, or ± coiled, several-seeded

30. Corolla persistent, enclosing fruit, yellow, 3.5–5 mm ..... TRIFOLIUM (2)

30' Corolla deciduous, yellow or not, 3.5–5 mm or not

31. Fruit spirally coiled (or sickle-shaped or straight), generally prickly; seeds 1–several ..... MEDICAGO (2)

31' Fruit not spirally coiled, not prickly; seeds 1–2

32. Fruit reniform, ridges generally net-like; corolla 2–3 mm ..... MEDICAGO (2)

32' Fruit ovate, ridges transverse to finely net-like; corolla 2.5–7 mm ..... MELILOTUS

29' Leaflet not toothed, not wavy

33. Plant not gland-dotted; seeds generally 2–several; fruit exserted from calyx or included except for beak

34. Inflorescence an umbel; fruit exserted from calyx or included except for beak ..... ACMISPON (3)

34' Inflorescence a raceme; fruit exserted from calyx ..... ASTRAGALUS (3)

33' Plant ± gland-dotted; seed 1; fruit generally included in calyx except for beak

35. Corolla cream to yellow; calyx conspicuously swollen in fruit ..... RUPERTIA

35' Corolla at least partly blue to purple; calyx swollen or not in fruit

36. Calyx swollen in fruit; bracts at each node, especially lower, of inflorescence united into fan-shaped, 3–5 toothed blade ..... BITUMINARIA

36' Calyx not (or only ±) swollen in fruit; bracts at nodes of inflorescence not united ..... HOITA

27' Leaflets > 3 on all or most leaves; fruit dehiscent or not

37. Leaf even-pinnate, main axis ending as a bristle or tendril or not

38. Leaflets ± 20–60; fruit 4–8 cm or 15–20 cm; plant annual, shrub, small tree ..... SESBANIA

38' Leaflets < 30; fruit generally < 8 cm; plant annual, per

39. Stipules leaflet-like, often > leaflets; style longitudinally folded; leaflets 4–6, glabrous ..... PISUM

39' Stipules generally not leaflet-like but sometimes ± = leaflets; style not longitudinally folded; leaflets 4–many, hairy or glabrous

40. Style ± flat, puberulent near ± middle for ± 1/3–1/2 length adaxially; leaflets ± rolled in bud ..... LATHYRUS (2)

40' Style generally not ± flat, puberulent at tip, all around or especially abaxially; leaflets folded in bud ..... VICIA

37' Leaf odd-pinnate, main axis ending as a leaflet

41. Corolla wings << keel; leaflets adaxially finely red-dotted; fruit 1-seeded, leathery, strongly net-ridged ..... ONOBRYCHIS

41' Corolla wings ± = keel; leaflets adaxially dark gland-dotted or not, not red-dotted; fruit not simultaneously 1-seeded, leathery, and strongly net-ridged

42. Plant gland-dotted on stems, leaflets, or both; fruit indehiscent

43. Fruit several-seeded, long-exserted from calyx, glabrous or with bristles or prickles; leaflets 6–10 mm wide ..... GLYCYRRHIZA

43' Fruit 1-seeded, included in calyx, glandular; leaflets generally < 6 mm wide

44. Petals from receptacle; stamens 10; inflorescence head-like or not ..... PSOROTHAMNUS (4)

44' Petals, except banner, from side or top of column of fused filaments; stamens 5 or 9–10; inflorescence not head-like

45. Plant prostrate to decumbent

46. Stem gland-dotted ..... DALEA (2)

46' Stem not gland-dotted ..... MARINA (3)

45' Plant ascending to erect

47. Inflorescence a dense spike; stamens 5 ..... DALEA (2)

47' Inflorescence an open raceme; stamens 9–10 ..... MARINA (3)

42' Plant not obviously gland-dotted; fruit dehiscent or not

48. Flowers 1–2 or several to many in umbel

49. Stipules gland-like, often not apparent; fruit exserted or not, ovate to oblong ..... ACMISPON (3)

49' Stipules conspicuous, scarious or leaflet-like; fruit exserted, generally linear to lanceolate

50. Inflorescence generally 10–20-flowered umbel; fruit indehiscent, segments 1–12 ..... CORONILLA

50' Inflorescence several-flowered umbel or 1–2-flowered; fruit dehiscent, segments 0 ..... HOSACKIA

48' Flowers (1–2 or) many in spike to raceme that is head-like or not

51. Seed 1; leaflet tip with gland; inflorescence a spike, dense, ± 1 cm ..... MARINA (3)

51' Seeds several; leaflet tip without gland; inflorescence a spike or raceme, dense or not, generally > 1 cm

52. Fruit indehiscent, breaking into 1-seeded segments; corolla 6–9 mm; leaflet generally < 6 mm ..... ORNITHOPUS

52' Fruit generally dehiscent (sometimes slowly so), not breaking into 1-seeded segments; corolla often > 9 mm; leaflet often > 6 mm

53. Style tip or stigma finely hairy; stipules spiny, free ..... PETERIA

53' Style tip and stigma glabrous; stipules not spiny, free or fused

54. Keel tip rounded to acute (or short-beaked); fruit 1-chambered, if ± 2-chambered then septum from lower suture, rarely fusing with narrow flange from upper suture ..... ASTRAGALUS (3)

54' Keel tip beaked; fruit ± 2-chambered, septum from upper suture, partial to complete ..... OXYTROPIS

