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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

ROSACEAE ROSE FAMILY

Daniel Potter & Barbara Ertter, family description, key to genera; treatment of genera by Daniel Potter, except as noted


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 per

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

4' Leaf 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. Leaflets lobed > 2/3 to midvein; annual, biennial; basal leaves withered at flower ..... POTERIDIUM

6' Leaflets 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; California Floristic Province (except High Sierra Nevada) ..... 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 North Coast, nw Klamath Ranges, n Outer North Coast Ranges ..... SANGUISORBA

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

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

8' Leaves 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. Leaf (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' Leaf ± 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; California Floristic Province, Great Basin Floristic Province ..... HORKELIA

19' Stamens 20; leaflets 15–35 per side; c&s High Sierra Nevada, East of Sierra Nevada ..... 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. Leaf 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' Leaf 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. Leaves 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 Desert Mountains ..... 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 California Floristic Province, Great Basin Floristic Province

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

27' Leaves 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. Leaves opposite; 1° leaflets 5–14 cm; inflorescence generally flat-topped; trunk bark peeling in strips; Channel Islands ..... LYONOTHAMNUS (2)

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

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

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

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

30' Stem 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' Leaves 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. Stem armed with thorns

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

34' Leaves 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' Stem generally not armed (thorny or not in Malus, Pyrus)

35. Leaf generally sharp-toothed

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

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

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

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

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

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

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

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

39' Leaves 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. Leaf veins palmate

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

41' Leaf 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' Leaf veins pinnate

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

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

44. Leaves opposite or in opposite clusters

45. Shrub 2–20 dm; petals 0 (1–5); pistil 1(2); fruit achene; East of Sierra Nevada, Desert (especially Desert Mountains) ..... COLEOGYNE

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

44' Leaves 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. Leaf generally entire; inflorescence raceme, pendent; flowers unisexual, occasionally bisexual; fruit drupes ..... OEMLERIA

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

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

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

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

52' Inflorescence 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 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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