Oxalidaceae: Oxalis Family
Yellow Wood-sorrel – Oxalis corniculata
Blooms:
Mar–June
Plant Height:
< 50 cm
Flower Size:
Medium
Origin:
Mediterranean
Habitat:
Weed of gardens and waste places
Notes:
This has bright yellow flowers like the other wood-sorrels, but they are a little larger (1.5 cm across). They usually have 2 red dots, or a red smear, at the base of each petal. There are 2–7 flowers, on short (< 2 cm) pedicels. Leaves may be green, or olive, or even purplish. The leaves are glabrous above, but with hairs on the margins. Leaflets are sometimes open, sometimes half-closed.
Dwarf Wood-sorrel – Oxalis micrantha
Blooms:
Apr–May
Plant Height:
< 20 cm
Flower Size:
Small
Origin:
South America
Habitat:
Foothill woodland, rock outcrops, disturbed places
Notes:
Like Hairy Wood-sorrel (Oxalis pilosa, see below), this has small, bright yellow flowers (just over 1 cm across). It can be distinguished by its long peduncles (up to 15 cm), each bearing 6–14 flowers. Leaflets are sparsely hairy. Its fruits are short (< 5 mm), ovoid to spheric in shape.
Redwood Sorrel – Oxalis oregana
Blooms:
Feb–Aug
Plant Height:
Creeping
Flower Size:
Medium
Origin:
Native
Habitat:
Redwood forests
Notes:
One of the few native Oxalis in Monterey County, this can carpet the ground in redwood forests. Flowers range from white to pale pink, often with an orange band at the base of the petals. The leaves have 3 lobes, each shaped like a heart. The leaves are a little larger than those of the Wood-sorrels, although they have a similar shape.
Bermuda Buttercup / Sourgrass – Oxalis pes-caprae
Blooms:
Nov–Mar
Plant Height:
15–30 cm
Flower Size:
Medium
Origin:
South Africa
Invasive?
Yes – moderate
Habitat:
Roadsides, disturbed areas, woodland
Notes:
Although invasive, this has attractive bright yellow flowers. They appear in profusion in late winter to early spring. The plant spreads by underground bulblets, so it’s very hard to eradicate. The origin of the common name is obscure – the plant neither is nor looks like a buttercup, nor does it come from Bermuda. Photo #1 by CJH.
Hairy Wood-sorrel – Oxalis pilosa
Blooms:
Feb–Sept
Plant Height:
< 50 cm
Flower Size:
Small
Origin:
Native
Habitat:
Sandy soils and brushy hills near coast
Notes:
Like Dwarf Wood-sorrel (Oxalis micrantha, see above), this has small, bright yellow flowers, just over 1 cm across. It can be distinguished by its shorter peduncles (< 2 cm), each bearing 1–3 flowers. Leaflets are densely hairy. Its fruits are much longer (12–18 mm), more or less cylindric in shape. Photo #2 by CJH.
