The Oxalis triangularis is a genus from the Oxalidaceae family and is also called purple shamrock, wood sorrel or false shamrock. The leaves look like those from the clover genus which are commonly called shamrock. This is why the Oxalis triangularis is called false shamrock. The Oxalis triangularis is native to Brazil.
The leaves and flowers of the Oxalis triangularis are edible. They taste a bit like lemon. They contain oxalic acid which is also present in for example rhubarb, cashew nuts, cocoa, spinach and soy products. There is some discussion on how health oxalic acid is. Just to be safe it is advised to eat only a small amount of it.
Often the false shamrock is described as a plant for indoors but this plant is excellent for in the garden as well. It is often said that false shamrock is not hardy but it is very hardy indeed.
The purple shamrock prefers a spot with bright light but not too much sun. A position in part shade gives the best results. Furthermore the Oxalis triangularis likes well-drained and not too moist soil.
The Oxalis triangularis does not like drought or too much heat. Then the leaves may die and they only reappear if it turns cooler and/or more moist. Temperatures between 60 and 75 ºF (15 and 25 ºC) during the day and not lower than 55 ºF (13 ºC) at night are most ideal. The leaves will also disappear if it is too cold. They will turn up again when it is warmer.
It is not a problem if the leaves die. The Oxalis triangularis grows from corms. The perennial goes into a dormancy period when there is too much heat, cold or drought. The corms of the Oxalis triangularis are orange and they spread gradually. You can dig up the orange corms during a dormancy period and divide them and bury them in the ground again. It does not matter how you bury them. This way you can propagate the wood sorrel. They usually come to live after some time.
Several weeks after the leaves have emerged above ground the flowers will develop. The flowers usually keep coming until the leaves wither. It may take young corms a bit longer to bloom.
In the evening (when it turns dark) the leaves and flowers of the false shamrock close. The leaves open when it gets light in the morning and the pink flowers open in the sun. The flowers rise above the leaves.
Characteristic: newly emerging every year
Deer resistant: yes
Exposure: part shade
Foliage color: red
Flower color: pink
Flowering time: June - October
Hardiness: -20 ºC (-4 ºF)
Height: 8 inches (20 cm)