Description
Oxalis – Shamrock – Wood-sorrel –
There are about 500 specious of fibrous rooted, bulbous, rhizomatous, or tuberous annual and perennials, some of which are invasive weeds, and a few weak stemmed subshrubs, in this genus. They occur in open habitats or in woodland, and widely distributed, with many species from South Africa, and South America. Those grown as ornamental are valued for their palmate, often clover like foliage (some have leaves that fold at night), and for their funnel to cup or bowl shaped, usually pink, white or yellow, 5 petaled flowers, sometimes umbel-like, and usually open only in sunlight, closing in dull weather or at night. Woodland species, such as O. acetosella and O. regana, are suitable for naturalizing in a shady site. Many of the hardy species from Southern Africa and South America, as various cultivars are suitable for a rock garden, raised bed, or trough.
Grow hardy woodland species in full or partial shade. Other hardy species need full sun and well drained, moderately fertile, humus rich soil. Divide in spring.
Prone to rust, seed smut, powdery mildew, fungal leaf spots, leaf miners , and spider mites.
O. oregana – Redwood Sorrel – This creeping, rhizomatous perennial from woodland in Western North America grows 8-10″ tall with an indefinite spread. It produces hairy, dark green leaves, each divided into 3 inversely heart shaped leaflets, to 1 1/4″ long. From spring to autumn on slender stems it carries solitary, cup shaped, rose pink, lilac, occasionally white flowers, to 1″ across.
Zones 7-9
