Oxalis megalorrhiza is a low-growing perennial herb, about 20 centimetres tall with a swollen rootstock and short frutticose stems leafy and ﬂoriferous only at apex. This species is singular for the great size of the root whence its trivial name. The heads of it resemble so many suffruticose stems. The shining, fleshy, deep green leaves form a small clump, whilst the flowers have yellow petals that are surrounded by distinctive heart-shaped sepals. This South American plant is better known by its synonym O. carnosa.