Pelargonium tetragonum (Square-stemmed Pelargonium)

Pelargonium tetragonum, commonly known as Four-angled Pelargonium or Square-stemmed Pelargonium, is a semi-succulent shrub native to the Eastern Cape of South Africa, valued for its unusual quadrangular stems and climbing or sprawling habit. It typically grows 2 to 4 feet tall, with fleshy, green stems marked by four distinct ridges that give the plant its characteristic angular form. Leaves are small, soft, and often short-lived, appearing along the nodes, while the structure of the stems remains the dominant visual feature. Pale pink to white flowers with delicate markings may appear in warm seasons but are secondary to the architectural growth.

This species prefers full sun to bright light and very well-drained soil, with moderate watering and thorough drying between cycles to prevent rot. It grows at a moderate pace and benefits from support or pruning to manage its somewhat lax, climbing habit. Suitable for USDA zones 10 to 11, it is sensitive to frost and should be protected below about 35 F. Pelargonium tetragonum performs well in containers and is often grown as a collector plant for its distinctive, almost succulent-like form.