Embossed color/colour photograph by J. McCombie.
Oxalis triangularis or Oxalis Regnellii, commonly called False Shamrock, is a species of edible perennial plant in the Oxalidaceae family. It is endemic to Brazil. This woodsorrel (Wood Sorrel) is typically grown as a houseplant but can be grown outside in USDA climate zones 8a-11, preferably in light shade. It has dainty pretty white to pale pink flowers.
The subspecies O. triangularis subsp. papilionacea, in particular its cultivar ‘Triangularis’, is highly popular as a pot plant and known as Love Plant, Purple Passion, Black False Shamrock, and Purple Shamrock.
The purple, triangular leaflets of O. triangularis move in response to light levels, opening in high ambient light (in the day) and closing at low light levels (at night). This movement is not due to growth and is instead powered by changes in turgor pressure in cells at the base of the leaf. It is an example of photonasty.
Most gardeners choose plants based on their flowers, but leaves are a big part of what we see year round. Triangularis leaves are a stellar purple, with deep rose patterning and a zippy geometric shape. For small plants with huge impact, mix triangular with silver leafed partners like Japanese ferns or artemesia or chartreuse mates as our photo shows. Exceptionally handsome in light colored ceramic pots. Also excellent as houseplants on a sunny windowsill for rich color all winter.