Oxalis smalliana
redwood sorrel
Pacific coast of western North America
Overview
Oxalis smalliana is a low, spreading perennial in the wood sorrel family that forms a creeping groundcover 2-6 inches (5-15 cm) tall in shaded forest. It spreads by scaly rhizomes, sending up clover-like leaves divided into three heart-shaped leaflets, each 0.5-1.5 inches (1.5-4 cm) wide, that fold downward at night and in bright sun. From spring into summer it bears solitary five-petaled flowers about 0.75-1 inch (2-2.5 cm) across, white to pale pink with darker veins, held just above the foliage. O. smalliana grows on the moist, humus-rich floor of coast redwood and mixed evergreen forests of California and adjacent regions, carpeting shaded slopes and streambanks. It needs cool, damp, shaded conditions and wilts quickly in heat, drought, or direct sun. The shallow rhizomes let it knit into broad mats but also make it sensitive to soil disturbance and compaction. The foliage has a sour, oxalic taste. It can spread widely where conditions suit, forming a continuous understory layer.
Native Range
Native to the Pacific coast of western North America, in the moist coast redwood and mixed evergreen forests of California and adjacent regions.Suggested Uses
Used as a shade groundcover under trees, in woodland gardens, and along damp, shaded paths. It knits into a continuous green carpet in moist redwood-forest conditions. Hot, dry, or sunny sites are unsuited to it.How to Identify
Appearance
Size & Dimensions
Height2" - 6"
Width/Spread1' - 2'
Bloom Information
Detailed Descriptions
Flower Description
white to pinkFoliage Description
greenGrowing Conditions
Sun Requirements
Tolerates up to 4 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Oxalis smalliana grows in part to full shade and cool, moist, humus-rich soil with a pH from about 5.0 to 6.5. It needs steady moisture and declines in heat, drought, and direct sun. The leaflets fold during midday sun and reopen in lower light. It spreads by rhizomes to form a groundcover and is propagated by dividing the rhizomes in spring or fall. A mulch of leaf litter keeps the roots cool and damp. No fertilizer is needed in woodland soil rich in organic matter.Pruning
No pruning is needed for this low groundcover. Tattered or frost-damaged leaves are removed to keep the mat fresh. Spread is limited by lifting and dividing the rhizomes.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons