Leaves typically divided into three leaflets, giving them the look of clover leaves. Flowers may be pink, white, rose, or yellow. Good in borders or pots. Resist deer.
O. acetosella. WOOD SORREL, SHAMROCK. Zones US, MS, LS, CS; USDA 6-9. From many northern temperate regions of the world. To 5 in. high, spreading widely by rhizomes. Typical clover-type leaves with three heart-shaped leaflets. Blooms in late spring, bearing 34-in.-wide, white flowers with purple to pink veins; blossoms rise just above the foliage. Can be somewhat invasive in its favored woodland conditions (moist, rich soil and partial shade). See also Shamrock.
O. adenophylla. Zones US, MS, LS, CS; USDA 6-9. Native to South America. Dense, compact, leafy tuft to 4 in. high, 6 in. wide. Each leaf has 9 to 22 crinkly, gray-green leaflets. In late spring, 4- to 6-in. stalks bear 1-in., bell-shaped flowers in lilac-pink with deeper veins. Good rock garden plant or companion to bulbs such as species tulips or smaller kinds of narcissus, either in pots or in the ground. Needs good drainage. Plant tubers in fall, setting 1 in. deep, 35 in. apart.
O. articulata crassipes (O. crassipes). PINK WOOD SORREL. Zones MS, LS, CS, TS; USDA 7-11. Probably from South America. Similar to but slightly less hardy than the species O. articulata rubra. Like that species, it often becomes a weed in lawns in the Lower and Coastal South and is highly susceptible to rust. Selection 'Alba' has white flowers; 'Rosea' naturally has pink flowers.
O. a. rubra (O. rubra). OXALIS, WOOD SORREL. Zones US, MS, LS, CS, TS; USDA 6-11. Native of Brazil and Argentina. Forms low mounds, 612 in. tall and wide. Cloverlike leaves with three notched leaflets. Showy flowers in pink, rose, or lavender with darker veins, late winter or early spring. Pretty as ground cover or in rock garden or front of border. In fertile, moist soil in the Lower and Coastal South, it may spread and become hard to eradicate. Very susceptible to rust.
O. brasiliensis. Zones CS, TS; USDA 9-11. Native to Brazil. To 6 in. high and wide, with purplish leaves to 1 in. long. Blooms in spring and summer, bearing inch-wide reddish purple flowers with a yellow throat. Plant bulbs in fall, setting them 1 in. deep, 35 in. apart. Best used in pots.
O. depressa. Zones MS, LS, CS, TS; USDA 7-10. Native to South Africa. Cloverlike leaves remain tidy at 4 in. tall. Rose-pink flowers open in a spiral to reveal a yellow throat. Best grown in a pot to contain its spread in warm zones.
O. purpurea. Zones MS, LS, CS, TS; USDA 7-11. Native to South Africa. Grows to 4 in. tall and 6 in. wide; dark green leaves have large (up to 112-in.-wide) leaflets. Bears 1- to 2-in., rose-red flowers over a long period in fall and winter. Spreads by bulbs and rhizome- like roots but is not aggressive or weedy. Plant bulbs in fall, setting them 1 in. deep, 35 in. apart. Improved kinds, sold under the name 'Grand Duchess', have larger flowers in rose-pink; and there are also 'Grand Duchess White' and 'Grand Duchess Lavender'.
O. tetraphylla. GOOD LUCK PLANT. Zones MS, LS, CS, TS; USDA 7-11. From Mexico. Forms a clump to 610 in. high and wide. Medium green leaves to 3 in. across have four leaflets instead of the usual three, each one banded purple toward the base. In 'Iron Cross', the purple markings are more extensive splotches that form a cross shape. Both species and selection are usually grown as foliage plants, but they bear attractive clusters of 1-in., reddish flowers with greenish yellow throats in spring and summer. Plant bulbs in fall1 in. deep, 35 in. apart.
O. triangularis (O. regnellii). Zones MS, LS, CS, TS; USDA 7-11. Native to South America. To 810 in. high, 1 ft. wide. Grows from rhizomes. Green leaves 13 in. across; tiny white blossoms in spring and summer. O. t. papilionacea (O. r. atropurpurea), called purple shamrock, features large, velvety purple leaves and pinkish lilac blossoms. Tolerates drought. Great garden plant.
O. versicolor. CANDY CANE SORREL. Zones MS, LS, CS, TS; USDA 7-11. Native to South Africa. To 36 in. high and 8 in. wide. Medium green leaves have deeply notched leaflets smaller than 12 in. wide. Funnel-shaped flowers are white, over 1 in. wide, with a crimson margin on the petal backs; buds also show striping. Plant bulbs in fall for spring flowers (set them 1 in. deep, 35 in. apart); bloom lasts for months.