It is a heteroecious rust and its aecia are produced on species of Oxalis, namely O. stricta, according to Arthur (1929).
2010, M. S. Patil, Anjali Patil, “16: The Rust Fungi: Systematics, Diseases and Their Management”, in Arun Arya, Analía Edith Perelló, editors, Management of Fungal Plant Pathogens, page 209