Purple Leaf Oxalis (oxalis triangularis): This appears to be the perennial plant, purple leaf oxalis, that can be grown as a garden annual (in full or partial sun) or as a houseplant in a sunny window. Needs regular water. It is a much better behaved Oxalis than other varieties. Do not allow plant to sit in water as this may lead to root rot. Feed with a slow-release fertilizer formulated for container plants. The rhizome can be divided to make new plants.