These irises are all in the series Sibiricae which have hollow flowering stems, triangular stigmas and capsules that are roundish to 3-angled in section with deltoid seeds.

Edwards (1976), Service (1990), McEwan (1996).

Source: Cooke, D. (2005). Iridaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.