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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.


Roots fibrous or woody; bulbs, tubers, or rhizomes often present. Stem: ± 0 or not. Leaf: stipules 0 or small; leaflets 3, generally ± obcordate [not], generally entire, generally green. Flower: petals clawed; styles erect or curved. Fruit: cylindric to spheric, explosively dehiscent. Seed: flat, often ridged; aril translucent.
500–950 species: especially temperate. (Greek: sour, from acidic taste) [Lourteig 2000 Bradea 7:201–629] Taxonomy difficult, needs study; generally heterostylous; many (especially aliens in California except Oxalis micrantha) ornamental; some noxious weeds; oxalates may be TOXIC to livestock; Oxalis latifolia Kunth possibly naturalized in Central Coast (Keil 30389, just north of San Simeon), differs from Oxalis purpurea in having flowers in umbel-like cyme; Oxalis hirta L. an historical waif (no recent collections), excluded.
Unabridged references: [Eiten 1963 Amer Midl Naturalist 69:257–309; Lourteig 1975 Phytologia 42:57–1979; Turner 1994 Phytologia 77:1–7]

Key to Oxalis

1. Petals yellow to yellow-orange, drying ± red or not

2. Annual; fruit < 5 mm ..... O. micrantha

2' Perennial herb; fruit >= 6 mm or 0

3. Leaves in loose, ± basal rosette; bulbs present ..... O. pes-caprae

3' Leaves cauline; bulbs 0

4. Petals 12–20 mm; North Coast ..... O. suksdorfii

4' Petals 5–12 mm; North Coast, elsewhere

5. Petals generally < 8 mm; taproot fibrous; stem rooting at nodes ..... O. corniculata

5' Petals generally 8–12 mm; taproot ± woody; stem not rooting at nodes (sometimes rooting at nodes in O. pilosa)

6. Hairs generally sparse, appressed or arched upward; pedicels > 2 × fruit ..... O. californica

6' Hairs dense, generally spreading; pedicels < 2 × fruit ..... O. pilosa

1' Petals white to pink, red, purple-rose, or purple

7. Bulbs 0

8. Rhizome woody, not creeping; disturbed places ..... O. articulata subsp. rubra

8' Rhizome fleshy, creeping; ± undisturbed forests

9. Flowers 1 ..... O. oregana

9' Flowers 3–9 in umbel-like cyme ..... O. trilliifolia

7' Bulbs present

10. Stem elongate ..... O. incarnata

10' Stem ± 0

11. Flowers in umbel-like cyme ..... [O. bowiei]

11' Flowers 1 ..... [O. purpurea]


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