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

Key to Geranium

View taxon page for Geranium

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

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

1. Perennial herb, from thick, scaly, underground 

2. Inflorescence 1-flowered ..... G. potentilloides

2' Inflorescence 2-flowered

3. Mericarp without  callus

3a. Petals 19–21 mm;  divided > 0.9 to base or midrib ..... G. palmatum [evidently known only from ± urban environments in California]

3a' Petals 7–11 mm; leaf divided 0.5–0.6 to base ..... G. pyrenaicum [neither naturalized nor escaped in California; collected only once, in 1914, on UC Berkeley campus]

3' Mericarp with basal callus

4. Petals glabrous adaxially,  at base

5. Petals 12–21 mm; fruit beak 27–44 mm ..... G. oreganum

5' Petals 3–8.1 mm; fruit beak 8.8–15.1 mm

6. Pedicel hairs , 0.2–0.6 mm ..... G. core-core

6' Pedicel hairs  or reflexed, not appressed, 0.2–2 mm ..... G. solanderi

4' Petals 1/3–3/4 hairy adaxially, ciliate at base or not

7. Nectaries woolly abaxially; petals white; stigmas 3–4 mm ..... G. richardsonii

7' Nectaries glabrous abaxially, hair-tufted at top; petals white to red-purple; stigmas 3–8 mm

8. Fruit narrow tip 5–6 mm, stigmas 6–8 mm; leaves 3–8 cm wide; petals 10–15 mm ..... G. californicum

8' Fruit narrow tip 3–4 mm, stigmas 3–6 mm; leaves 7.1–16 cm wide; petals 17–20 mm ..... G. viscosissimum

1' Annualbiennial, from short, ± slender roots

9. Fertile stamens 5 (outer 5 lacking anthers) ..... G. pusillum

9' Fertile stamens 10 (inner 5 and outer 5 all with anthers)

10. Sepals with transverse flaps between lengthwise keels ..... G. lucidum

10' Sepals without flaps or keels

11. Mericarp ribbed or ± net-like or transversely wrinkled

12. Mericarp without collar-like rings or fibers at tip, transversely wrinkled ..... G. molle

12' Mericarp with 1–5 collar-like rings and long fibers at tip, ribbed or ± net-like

13. Petals 5–9.5 mm; mericarp with 3–5 collar-like rings at tip; anthers ± yellow ..... G. purpureum

13' Petals 10–14 mm; mericarp with 1–3 collar-like rings at tip; anthers ± purple ..... G. robertianum

11' Mericarp smooth (although sometimes ± ribbed or hairy or bristly)

14. Mericarp base with prong, without callus ..... G. dissectum

14' Mericarp base without prong, generally with callus

15. Mericarp glabrous except base generally ciliate ..... G. aequale

15' Mericarp ± hairy throughout except basal callus bristly

16. Fruit beak with a narrow tip < 2 mm

17. Pedicel hairs spreading, glandular and nonglandular, sometimes also reflexed, not appressed, nonglandular; mericarp hairs dense, 0.5–1.8 mm ..... G. carolinianum

17' Pedicel hairs reflexed, appressed, nonglandular; mericarp hairs sparse, 0.2–0.7 mm ..... [G. texanum]

16' Fruit beak with a narrow tip 2–6 mm

18. Peduncles without glandular hairs ..... G. columbinum

18' Peduncles with glandular hairs

19. Leaf divided 0.85–0.95 to base ..... G. bicknellii

19' Leaf divided 0.55–0.65 to base ..... G. rotundifolium



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

Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on .

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