OXALIS. Nearly worldwide. In addition to some much-despised weeds, this group includes a broad assortment of highly ornamental perennials. They grow from underground rhizomes, which may develop bulbous structures. Most have clover-like leaves and relatively large 5-petalled flowers of white, pink to red, purple or yellow. Many are suitable for container and rock garden use. Sun, most soils, moderate watering during growth and bloom, except as noted. Those which die down at some point may go completely dry for the dormant season, though most will tolerate moisture at this time. Hardy to 20oF or below, less as indicated (where known).
bowiei (purpurata bowiei). One of the most robust of the “bulbous” types, growing from fall to early spring. It has large, shiny bright green leaves on 8-12" stalks. Large purplish red blossoms are held above the foliage in umbrella-like clusters for several weeks in fall and early winter. The leaves are damaged at 20o, though the plants quickly recover.
braziliensis. A bulbous perennial, with three-parted leaves rising 2-3" from the ground. Above them are displayed many purplish pink flowers with yellow centers, about 1" broad, in May and June. One of the more tender species, best protected from hard winter frosts.
deppei. Another bulbous species, growing and blooming in the summer months. It has large, purple-marked leaves on stalks up to 10" high, and umbrella shaped clusters of (in this selection) coral red blossoms.
hirta. One would hardly guess this to be an Oxalis when not in bloom. It grows from densely clustered “bulbs”, with erect 6-12" stems and brushes of narrowly parted bluish green leaves, appearing in early fall and lasting until spring. One-inch blossoms painted bright rose pink are clustered at the stem ends in fall and winter.
magellanica. A dense, ground-hugging carpet with small, dark, 3-parted leaves. It is dotted in summer with 1/2" white flowers. A plant for rock gardens and containers.
obtusa. This is my unconditional favorite of the bulbous species. It forms very tight summer-deciduous clumps, from which clusters of small grey-green leaves barely rise. Nestled among them for several weeks in spring are soft silvery pink blossoms up to 1" broad. One of the best of all oxalis for the rock garden. About 20oF.
oregana. Redwood sorrel. An evergreen, carpeting native of our coastal redwoods, grown primarily as a foliage plant and ground cover. Its large (2" or more), broadly parted leaves are marked with light green or white. In spring large, white to light pink blossoms with darker veining are carried above the foliage on individual stems. Our latest selection, ‘Forest Lights’, has unusually dark green leaves, with bright purplish red undersides and stalks. Shade, constant moisture. 0-10oF.
rubra. A tuberous species, virtually evergreen in our climate. It makes small, dense colonies of shoots, with bright green leaves rising on slender stalks 6-12" long. It produces a continual show of flowers for many weeks in spring and summer. Those of the current selection are about 1” in diameter and deep pink in color (there are many other forms). 20oF. or less.