Oxalis

Oxalis

Oxalis acetosella
Also called Oxalis montana for the North American subspecies. A perennial, reaching up to 6 inches in height, that is native to Eurasia ( from Iceland to Japan; south to the Mediterranean ) and North America ( from Sudbury, Ontario to Labrador; south to northern Wisconsin to northern Michigan to far northern Georgia in the Smoky Mountains to central Pennsylvania ). It is found in moist woodlands in the wild.
The leaves are composed of 1 to 3 leaflets, each up to 0.5 inches wide. The foliage is luxuriant bright green.
The white ( veined lilac ) flowers, up to 1.2 inches wide, are borne mid to late spring, sometimes repeating during summer into early autumn.
Hardy zones 3 to 6 in shade on moist, humus-rich soil.

Oxalis crassipes
An attractive rhizomatous, clumping perennial, reaching up to 1 x 12 inches in size, that is native to South America ( Argentina, Uruguay & southern Brazil ). It can be planted about 1 foot apart to be used as groundcover. It is NOT invasive. The white to pale pink flowers appear late spring into late autumn in temperate climates. Hardy zones 6 to 10 ( reports of 5a on protected sites ) in partial shade on moderately moist, fertile, humus-rich, well drained soil. Cut back foliage once the plant goes dormant. Mulch heavily with pine needles during winter in cold climates. In very mild climates, it goes summer dormant. In temperate climates, it does the opposite going dormant during the winter.

'Rosea'
Just a named clone with deeper pink flowers; otherwise identical to species.

* photos taken on Oct 2 2014 in Burtonsville, MD

Oxalis oregona ( Redwood Sorrel )
A perennial, reaching up to 10 inches in height, that is native to coastal rainforests in western North America ( from the Queen Charlotte Islands to Vancouver, British Columbia; south to coastal central California ).
The foliage is luxuriant mid-green, blotched bright green in the center.
The white to pale pink ( veined purple ) flowers, up to 0.8 inches in length, are borne mid-spring to early autumn.
Hardy zones 7 to 9 in shade on just about any moist, humus-rich soil.

* historical archive photo

Oxalis regnellii
An attractive clumping bulbous perennial, reaching up to 9 x 15 inches in size, that is native to South America. It can be planted about 1 foot apart to be used as groundcover. It is NOT invasive. The flowers are white. Hardy zones 7 to 10 ( reports of 6 on protected sites ) in partial shade on moderately moist, fertile, humus-rich, well drained soil. Cut back foliage once the plant goes dormant. Mulch heavily with pine needles during winter in cold climates. In very mild climates, it goes summer dormant. In temperate climates, it does the opposite going dormant during the winter.

* photo taken on May 5 2018 in Columbia, MD

* photo taken on May 19 2019 in Columbia, MD

* photos taken on May 19 2020 in Columbia, MD

'Atropurpurea
Stunning foliage that is intense deep purple with a broad black border.
The bright pink flowers provide great contrast with the flowers.

* photo taken on May 27 2012 in Columbia, MD

* photos taken on Oct 21 2014 @ Smithsonian Inst., Washington, DC

* photo taken on May 27 2017 @ Meadowlark Botanical Gardens, Vienna, VA

* photo taken on June 26 2018 in Columbia, MD

* photo taken on May 28 2019 in Columbia, MD

* photo taken on June 18 2019 in Columbia, MD

* photo taken on June 7 2021 in Columbia, MD

* photo taken on July 20 2022 in Columbia, MD

Oxalis rosea ( Pink Sorrel )
A non-tuberous annual, reaching up to 15 x 12 inches in size, that is native to Chile. This is not to be confused with Oxalis crassipes 'Rosea' which is a perennial.
The flowers are bright pink to deep pinkish-red. Flowering time is often late spring into early summer but varies upon the climate in which it grows.
Hardy zones 7 to 10 in full sun on moderately moist, fertile, well drained soil. Sow seed directly where you want it to grow and do not cover them.

Oxalis violacea ( Violet Wood Sorrel )
A fast spreading perennial, reaching up to 16 inches in height, that is native to moist meadows and open woods in central and eastern North America ( from southwest Colorado to central North Dakota to central Wisconsin to far southern Michigan to far southwestern New York State to New Hampshire and Massachusetts; south to southeast Arizona to eastern Texas to far northwest Florida to central South Carolina ). It is endangered in Michigan, New Hampshire; endangered in New York State, Connecticut and Massachusetts. In the Windsor/Essex County, Ontario region; it was found on the Ohio shore during the 1800s where it was moderately common.
The leaves are composed of 3 leaflets. The foliage is blue-green above, green to red-purple beneath.
The violet flowers are borne mid-spring to early summer.
Hardy zones 4 to 8 in partial to full shade on moderately moist, well drained soil.

Oxalis vulcanicola

'Sunset Velvet'

* photo taken on Apr 24 2024 in Elkridge, MD

'Zinfandel'
A tender perennial ( annual in cool climates ), reaching up to 10 x 12 inches.
The velvety foliage is deep purplish-red.
The abundant, bright yellow flowers are borne late spring to late summer. It is sterile and therefore non-invasive.
Hardy zones 9 to 11 in full sun to partial shade on well drained soil. It is very drought tolerant.

* photo taken on Apr 24 2024 in Elkridge, MD