The Jepson Herbarium
		University of California, Berkeley

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Annual to tree, glandular or not.
Leaf: simple to palmately or pinnately compound, generally alternate; stipules free to fused (0), persistent to deciduous.
Inflorescence: cyme, raceme, panicle, cluster, or flowers 1; bractlets on pedicel (" pedicel bractlets") generally 0–3(many), subtended by bract or generally not.
Flower: generally bisexual, radial; hypanthium free or fused to ovary, saucer- to funnel-shaped, subtending bractlets (" hypanthium bractlets") 0–5, alternate sepals; sepals generally 5; petals generally 5, free; stamens (0,1)5–many, anther pollen sacs generally 2; pistils (0)1–many, simple or compound, ovary superior to inferior, styles 1–5.
Fruit: 1–many per flower, achene ( fleshy-coated or not), follicle, drupe, or pome with generally papery core, occasionally drupe-like with 1–5 stones.
Seed: generally 1–5 (per fruit, not per flower).
110 genera, ± 3000 species: worldwide, especially temperate; many cultivated for ornamental, fruit, especially Cotoneaster, Fragaria, Malus, Prunus, Pyracantha, Rosa, Rubus. [Potter et al. 2007 Plant Syst Evol 266:5–43] Number of teeth is per leaf or leaflet, not per side of leaf or leaflet, except in Drymocallis. —Scientific Editors: Daniel Potter, Thomas J. Rosatti.
Unabridged references: [Robertson 1974 J Arnold Arbor 55:303–332, 344–401, 611–662]

Key to Rosaceae

1. Annual to perennial herb

2. Plant 1–2 m; leaves 2–3-pinnately compound; flowers unisexual; fruit follicles ..... ARUNCUS

2' Plant generally < 1 m; leaves simple to 1-ternately or 1-palmately or 1-pinnately compound, including 2-ternately dissected; flowers generally bisexual; fruit achenes or follicles

3. Petals 0, sepals generally 4; fruits 1(3) per flower, inside ± urn-shaped hypanthium

4. Lf palmately lobed; inflorescence few-flowered cluster, axillary, ± hidden by sheathing stipules; hypanthium not hardened in fruit; annual ..... APHANES

4' Lf pinnately compound; inflorescence head or spike, axillary or terminal, not hidden; hypanthium ± hardened in fruit; generally per

5. Hypanthium ± prickly, not angled in fruit; stamens 2 or 4 ..... ACAENA

5' Hypanthium not prickly, 4-angled in fruit; stamens 0–many

6. Lflets lobed > 2/3 to midvein; annual, biennial; basal leaves withered at flower ..... POTERIDIUM

6' Lflets toothed < 1/3 to midvein; perennial herb; basal leaves not withered at flower

7. Largest leaflet blade generally 5–20 mm, on stalk generally 1–4 mm, teeth generally < 15; stamens many, filaments thread-like; open, especially disturbed areas; CA-FP (except SNH) ..... POTERIUM

7' Largest leaflet blade 25–50 mm, on stalk 3–25 mm, teeth generally > 15; stamens 2–4, filaments not thread-like; bogs, streams; c NCo, nw KR, n NCoRO ..... SANGUISORBA

3' Petals, sepals generally 5; fruits 1–many per flower, on or outside shallow to ± obconic hypanthium

8. Lvs ± 2-ternately dissected, segments linear; fruit follicles ..... LUETKEA (2)

8' Lvs simple to compound, ternately compound or not but not ternately dissected, segments linear or not or 0; fruit achenes, sometimes fleshy-coated (Rubus) or on fleshy receptacle (Duchesnea, Fragaria)

9. Hypanthium obconic to cup-shaped, rim with hooked bristles; inflorescence ± raceme ..... AGRIMONIA

9' Hypanthium generally shallower than obconic to cup-shaped, rim without hooked bristles; inflorescence generally cyme or flowers 1

10. Hypanthium bractlets 0; achenes fleshy-coated, finely hairy ..... RUBUS (3)

10' Hypanthium bractlets generally present; achenes not fleshy-coated, generally glabrous (except Geum)

11. Style continuous to fruit, if not or inconspicuously hooked then plumose — leaves 1-pinnately compound ..... GEUM

11' Style jointed to fruit, not hooked, not hairy

12. Lf (sub)palmately to ternately compound

13. Receptacle in fruit strawberry-like (enlarged, red, fleshy); stolons generally present; petals white or yellow; leaves ternately compound

14. Petals yellow; flowers 1 from axils of leaves on stolons; hypanthium bractlets generally wider than sepals ..... DUCHESNEA

14' Petals generally white; flowers 1–several from axils of basal leaves, stolons leafless; hypanthium bractlets narrower than sepals ..... FRAGARIA

13' Receptacle in fruit not strawberry-like; stolons 0; petals ± yellow; leaves pinnately, palmately, or ternately compound

15. Stamens 5; petals ± 1 mm; leaflets 3, generally 3-toothed at tip ..... SIBBALDIA

15' Stamens 10–25; petals (2)4–20 mm; leaflets 3–7, generally > 3-toothed ..... POTENTILLA (2)

12' Lf ± 1-pinnately to subpalmately compound

16. Petals dark red, elliptic to ± ovate, << sepals ..... COMARUM

16' Petals yellow to white, elliptic to obcordate (linear), < to > sepals

17. Style fusiform, attached below fruit middle ..... DRYMOCALLIS

17' Style slender throughout or widest near base, generally attached below fruit tip

18. Hypanthium cup-like, ± flat-bottomed; filaments generally ± flat, often forming tube; petals white or ± pink

19. Stamens 10; leaflets 2–15 per side; CA-FP, GB ..... HORKELIA

19' Stamens 20; leaflets 15–35 per side; c&s SNH, SNE ..... HORKELIELLA

18' Hypanthium ± shallow, if cup-like, not flat-bottomed; filaments generally thread-like, not flat (except ± flat in Ivesia argyrocoma var. argyrocoma), not forming tube; petals white to yellow

20. Plant generally hanging clump or rosette in vertical rock crevices, ± resin-scented ..... IVESIA (2)

20' Plant not hanging clump or rosette, generally not in vertical rock crevices, resin-scented or not

21. Lf generally ± cylindric; leaflets 4–80 per side; pistils 1–8(20); stamens 5–20(40); petals 1–5(7) mm, linear to obovate or round ..... IVESIA (2)

21' Lf generally ± flat; leaflets 2–8(13) per side; pistils generally > 10; stamens 20–25; petals (2)4–20 mm, generally ± widely obcordate ..... POTENTILLA (2)

1' Subshrub to tree

22. Lvs deeply lobed (generally to midrib) or compound

23. Ovary generally inferior, chambers 1–5; styles 1–5; fruit pome ..... SORBUS

23' Ovary superior, chamber 1; style 1; fruit achene or follicle

24. Pistils generally 10–many

25. Petals yellow; hypanthium bractlets 5; style attached near fruit base ..... DASIPHORA

25' Petals white to red; hypanthium bractlets 0 (5 in Fallugia); style attached at fruit tip

26. Plant not prickly; leaves pinnately lobed, rusty-scaly abaxially, margins rolled under; style plumose in fruit; e DMtns ..... FALLUGIA

26' Plant generally prickly; leaves pinnately to palmately compound, not rusty-scaly, margins not generally rolled under; style short-hairy to ± glabrous in fruit; generally CA-FP, GB

27. Lvs pinnately compound; hypanthium urn-shaped; fruit not on spongy receptacle, generally enclosed in fleshy hypanthium ..... ROSA

27' Lvs palmate-lobed or -compound; hypanthium flat to saucer-shaped; fruit on spongy receptacle, not enclosed by hypanthium (aggregate raspberry- or blackberry-like) ..... RUBUS (3)

24' Pistils 1–6

28. Lvs opposite; 1° leaflets 5–14 cm; inflorescence generally flat-topped; trunk bark peeling in strips; ChI ..... LYONOTHAMNUS (2)

28' Lvs alternate or clustered; 1° leaflets or lobes generally < 5 cm; inflorescence not flat-topped; trunk bark generally not peeling in strips; mainland

29. Lf 3–9-lobed; inflorescence generally 1-flowered; styles in fruit 2–6 cm, plumose ..... PURSHIA (4)

29' Lf (1)2–3-pinnate- or -ternate-dissected or -compound; inflorescence raceme or panicle; styles in fruit generally << 1 cm, not plumose

30. St ± prostrate to decumbent; plant < 2 dm; leaves ternately dissected, not glandular, not strong-smelling ..... LUETKEA (2)

30' St ascending to erect; plant > 2 dm; leaves pinnately compound, glandular, strong-smelling

31. Pistil 1(2); ovule 1; fruit achene; leaves 2–3-pinnately compound ..... CHAMAEBATIA

31' Pistils 4–5; ovules generally >= 2; fruit follicle; leaves (1)2-pinnately compound ..... CHAMAEBATIARIA

22' Lvs simple, lobed (deeply so only in Crataegus monogyra) or unlobed

32. Ovary inferior or 1/2-inferior, chambers generally 2–5; fruit a pome with generally papery core, occasionally drupe-like with 1–5 stones

33. St armed with thorns

34. Lvs ± ovate, deciduous, generally ± lobed above middle, toothed; larger leaves > 3 cm wide; fruit red to black ..... CRATAEGUS

34' Lvs generally oblanceolate, narrowly oblong, narrowly obovate, or narrowly elliptic, ± evergreen, unlobed, entire to toothed; larger leaves < 2.5 cm wide; fruit orange to red ..... PYRACANTHA

33' St generally not armed (thorny or not in Malus, Pyrus)

35. Lf generally sharp-toothed

36. Infl many-flowered panicle; petals < 4 mm; fruit 5–10 mm diam ..... HETEROMELES

36' Infl few-flowered cluster; petals 10–15 mm; fruit >= 10 mm diam

37. Fr generally ± spheric, flesh not gritty ..... MALUS

37' Fr generally ± obovoid, flesh gritty ..... PYRUS

35' Lf entire, minute-gland-toothed, or above middle toothed

38. Lvs ± clustered on short-shoots, petiole ± 0 ..... PERAPHYLLUM

38' Lvs evenly distributed on branches, twigs, petiole > ± 0

39. Lvs generally serrate above middle, deciduous; fruit a pome of 2–5 papery segments, generally blue-black ..... AMELANCHIER

39' Lvs entire, deciduous, or evergreen; fruit a pome, drupe-like with 2–5 stones, orange to red..... COTONEASTER

32' Ovary superior (sometimes hidden in funnel- or urn-shaped hypanthium), chamber generally 1; fruit not a pome

40. Lf veins palmate

41. Lf blade 3(5)-lobed above middle, generally wedge-shaped, margin not toothed, rolled under; flowers 1 ..... PURSHIA (4)

41' Lf blade generally 3–7-lobed below middle, not wedge-shaped, margin ± toothed, ± flat; flowers in cluster of several to many

42. Petals 2.5–3 mm; pistils 1–5 (if 3–5, fused below middle); inflorescence umbel-like cluster, not flat-topped; fruit follicles ..... PHYSOCARPUS

42' Petals 4–30 mm; pistils 5–150; inflorescence raceme- or panicle-like cyme, ± flat-topped; fruit fleshy-coated achenes (aggregate ± raspberry-like) ..... RUBUS (3)

40' Lf veins pinnate

43. Plant matted, scapose; rosettes many — generally on limestone ..... PETROPHYTUM

43' Erect shrub or tree, not scapose; rosettes 0

44. Lvs opposite or in opposite clusters

45. Shrub 2–20 dm; petals 0 (1–5); pistil 1(2); fruit achene; SNE, D (especially DMtns) ..... COLEOGYNE

45' Tree 40–150 dm; petals 5; pistils 2; fruit follicle; ChI ..... LYONOTHAMNUS (2)

44' Lvs alternate or in alternate clusters

46. Pistil generally 1

47. Hypanthium cup- to urn-shaped, deciduous in fruit; style not tapered to stigma; fruit drupe ..... PRUNUS

47' Hypanthium ± funnel-shaped to obconic, persistent in, ± enclosing fruit; style tapered to stigma; fruit achene or achene-like

48. Hypanthium 0.6–3.2 mm; petals 1.5–2.5 mm; inflorescence many-flowered panicle; leaf linear to oblanceolate or sickle-shaped, margin not rolled under ..... ADENOSTOMA

48' Hypanthium 2–14 mm; petals 0 or 6–8 mm; inflorescence 1–18-flowered cluster; leaf linear to round, margin generally rolled under

49. Petals 0; leaf toothed or not, lobes 0 ..... CERCOCARPUS

49' Petals 6–8 mm, white to cream; leaf generally not toothed, lobes 3–9 ..... PURSHIA (4)

46' Pistils generally 2–6

50. Lf generally entire; inflorescence raceme, pendent; flowers unisexual, occasionally bisexual; fruit drupes ..... OEMLERIA

50' Lf lobed or toothed; inflorescence umbel-like cluster, panicle, or flower 1, spreading to erect; flowers bisexual; fruit achenes or follicles

51. Lf generally widest above middle, margins with 3–9 lobes, generally 0 teeth, ± strongly rolled under; flowers 1 ..... PURSHIA (4)

51' Lf generally widest at or below middle, margins with ± 0 lobes, generally with teeth, not rolled under; flowers generally 3–many

52. Infl umbel-like cluster, flowers generally 3–5; petals 4–6 mm; stamens ± 50, sepals ± toothed ..... NEVIUSIA

52' Infl raceme or panicle, flowers many; petals 1.5–2 mm; stamens generally < 50, sepals not toothed

53. Petals generally white; hypanthium saucer-shaped; stigma ± 2-lobed; fruit 5 achenes ..... HOLODISCUS

53' Petals pink to rose; hypanthium obconic to bell-shaped; stigma head-like; fruit 5 follicles ..... SPIRAEA

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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