Jepson eFlora: Key page
Vascular Plants of California
Key to families | Table of families and genera

Key to Rosa

View taxon page for Rosa

(For a list of species in Rosa, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Leaflets << 1 cm, toothed ± 1/2 to base;  densely prickly – PR ..... R. minutifolia

1' Leaflets generally > 1 cm, toothed < 1/4 to base; hypanthium glabrous to stalked-glandular

2. Sepals with toothed lateral prickles  side-to-side, curved

3. Hypanthium 1–2 mm wide at flower, 5–7 mm wide at fruitpistils generally < 10 ..... R. multiflora

3' Hypanthium 4–5 mm wide at flower, 10–20 mm wide at fruit; pistils > 10

4. Leaves and sepals ± glandless; petals white to pink; terminal  ±  ..... R. canina

4' Leaves and sepals glandular; petals pink; terminal leaflet generally  to ± widely obovate ..... R. rubiginosa

2' Sepals generally  (tip sometimes toothed); prickles compressed or slender, straight or curved

5. Sepals deciduous in fruit; hypanthium 1.5–2 mm wide at flower; pistils 5–10; sepal tip generally << body; petals ± 10 mm – leaflets glabrous, flowers 1–3;  generally stalked-glandular ..... R. gymnocarpa

6. Leaflets generally (5)7–9; terminal leaflet tip generally ± , ± 10–30 mm; pedicels ± 15–30 mm; plants to ± 5–20 dm, generally in shade on non-ultramafic substrates; widespread ..... var. gymnocarpa

6' Leaflets generally 5(7); terminal leaflet tip widely obtuse to rounded, 4–20 mm; pedicels ± 10–15 mm; plants to generally 3–6 dm, full sun on ultramafic substrates; KR ..... var. serpentina

5' Sepals persistent; hypanthium 2.5–7 mm wide at flower; pistils generally > 10; sepal tip ± = or often > body; petals 10–25 mm

7. Dwarf, openly rhizomed shrubs, generally 1–5(10) dm; leaflet tip often ±  –  margins generally ± glandular, generally double-toothed

8. Hypanthium stalked-glandular – prickles generally ± slender, often many; NW, CW, MP(1 site), 150–1550(1950) m ..... R. spithamea

8' Hypanthium generally glandless, rarely sparsely glandular

9. Prickles few, paired, ± thick-based; terminal leaflet generally widely obovate; flower 1–2(7); CaR, SN, 700–2500 m ..... R. bridgesii

9' Prickles generally many, generally not paired, both slender and ± thick-based; terminal leaflet generally ± elliptic; flowers generally 1–5; CW, generally < 300 m ..... R. pinetorum

7' Open or thicket-forming shrubs, generally > 5 dm; leaflet tip not truncate

10. Terminal leaflet ± obovate-elliptic, widest at or above middle; leaf axis finely velvety, hairs ± 0.1 mm (glabrous), glandless; prickles slender to ± thick-based, generally ± straight; sepals glandless (in California); CaRH, SNH, Teh, TR, GB, DMtns ..... R. woodsii

11. Prickles generally many, 2–10(13) mm, often ± thick-based, internodal prickles generally present in inflorescence; c&s SNH, Teh, TR, SNE, DMtns, s DMoj exc DMtns (Box S Springs, Cushenbury Springs) ..... subsp. gratissima

12. Leaf axis finely velvety; c&s SNH, Teh, TR, SNE, DMtns ..... var. gratissima

12' Leaf axis glabrous; s DMoj exc DMtn (Box S Springs, Cushenbury Springs) ..... var. glabrata

11' Prickles few to many, 2–7 mm, slender, internodal prickles generally 0 in inflorescence; CaRH, n SNH, MP, n SNE ..... subsp. ultramontana

10' Terminal leaflet generally ovate to elliptic, generally widest at or below middle; leaf axis variously hairy, hairs to 1 mm, sometimes glandular; prickles generally ± thick-based, often curved; sepals often glandular; CA-FP, adjacent DMoj

13. Flowers generally 1(6); hypanthium generally 5–7 mm wide at flower, (10)13–20 mm wide at fruit, generally ± sphericachenes generally 4.5–6 mm – prickles to 20 mm, generally ± compressed, ± straight to ± curved; sepal tips generally > body, toothed ..... R. nutkana

14. Leaflets generally ± single-toothed, generally glandless; prickles generally few; NCoRO, KR, CaRH; 750–1500 m ..... subsp. macdougalii

14' Leaflets double-toothed, ± glandular especially beneath; prickles generally many; NCo, NCoRO, CCo; < 700 m ..... subsp. nutkana

13' Flowers 1–many; hypanthium 2.5–5.5 mm wide at flower, 7–15(20) mm wide at fruit, spheric to (ob)ovoid; achenes 3–5 mm

15. Prickles generally thick-based, generally curved (straight), few to many; leaflets and leaf axis generally ± shaggy-hairy, hairs to 1 mm;  generally ± hairy; hypanthium generally (ob)ovoid, glabrous to sparsely hairy, neck 2–4.5 mm wide at flower ..... R. californica

15' Prickles slender to ± thick-based, straight (± curved), 0–few; leaflets and leaf axis ± glabrous to ± hairy, hairs 0.1–1 mm; pedicels generally glabrous (except for glands); hypanthium spheric to ovoid, glabrous, neck ± 2 mm wide at flower ..... R. pisocarpa

16. Flowers 1–3(10); sepals generally glandless; prickles 0 to paired at ; leaflets generally 5(7) ..... subsp. ahartii

16' Flowers (1)3–10; sepals generally glandular; prickles generally paired at nodes; leaflets generally (5)7(9) ..... subsp. pisocarpa


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Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, [accessed on ]

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