Oxalis articulata has a large range from southeastern Brazil, Uruguay and Argentina. The species can be distinguished from the very similar-looking Oxalis floribunda based on the often thick and dense pubescence on the leaves. It grows from hard woody round rhizomes which are articulated together and can be deep or on near ground surface. This species is one of the oldest and most widely grown species of the genus in horticulture and thus a number of cultivars have arisen. In general, the species and their cultivars are summer growers, some being able to take more heat than others. Grow the rhizome in a well-drained mix and give the plants plenty of water and good fertilizers during the growing season. If treated well, they will continue blooming in various flushes throughout the season. During the winter, allow the medium to dry out somewhat, but it is not necessary (and not recommended) to completely dry out the medium.
The photo below by Nhu Nguyen shows a rhizome.
Oxalis articulata ssp. articulata has large, dense hairs on the leaves. The flowers have pubescence in exposed areas at the bottom of the petals. Photo by Nhu Nguyen.
Oxalis articulata ssp. rubra has pink flowers and two tiny oxalate deposits on each sepal. Photo by Nhu Nguyen.
Oxalis articulata ssp. rubra 'Pink Dream' is a selection from ssp. rubra made by Komoriya Nursery, Japan. It has light pink flowers. Photos by Nhu Nguyen.
Oxalis articulata 'Brasilian Pink' is a selection from ssp. rubra made by Komoriya Nursery, Japan. It has pink flowers, but darker than 'Pink Dream'.
Oxalis articulata f. crassipes is the white form of the species. Sometimes the pink forms are mistakenly called crassipes.