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 

caudex 

Generally short, sometimes woody, more or less vertical stem of a perennial, at or beneath ground level.

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

2' Inflorescence 2-flowered

3. Mericarp without 

basal 

At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary.

 callus

3a. Petals 19–21 mm; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

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, 

ciliate 

Having generally straight, conspicuous hairs along margins or edges.

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 

reflexed 

Abruptly bent or curved downward or backward.

, 

appressed 

Parallel or nearly parallel to and often in contact with surface of origin; used to describe the disposition of hairs, leaves, pedicels, etc.

, 0.2–0.6 mm ..... G. core-core

6' Pedicel hairs 

spreading 

Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal.

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' Annual, biennial, 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

Contact/Feedback

Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, https://ucjeps.berkeley.edu/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 .

We encourage links to these pages, but the content may not be downloaded for reposting, repackaging, redistributing, or sale in any form, without written permission from The Jepson Herbarium.