My sister's had this Oxalis (indoors) for some 20 years. The top of the foliage is green, and the undersides are a light purple. The flowers are white. The closest we've been able to find Online is Oxalis triangularis 'Fanny', but the similar ones On Google images are on individual Flikr accounts. The nursery images for 'Fanny' are green with white/silver variegation.