Solanum shirleyanum occurs in high rainfall areas of southeastern Queensland, and extends to near Murwillumbah in New South Wales. It grows on the margins of notophyll rainforest where Eucalyptus grandis is often prominent. Soils are infertile, and associated species may include Caldcluvia paniculosa and Callicoma serratifolia. It occurs at relatively low altitudes, although reaching 560 metres in the Conondale Ranges.
Solanum shirleyanum is a typical member of Solanum subgenus Leptostemonum. It is placed into the S. ferocissimum group (Group 13) by Bean (2004) on morphological grounds; its phylogenetic position has not been investigated using molecular data.
Solanum shirleyanum is related to both S. stelligerum and S. corifolium, and Domin considered that it was a hybrid between these two species. However, fieldwork of A. R. Bean has shown that S. shirleyanum should be regarded as a species in its own right. It forms populations uniform in morphology, flowers and fruits freely, and can occur in areas geographically remote from the postulated parents.
It differs from S. corifolium by the smaller flowers and fruits, more slender corolla lobes, and leaf stellae with conspicuous central rays. It differs from S. stelligerum by the shorter petioles, leaves with stellae all sessile and having shorter central rays, smaller fruits, larger seeds and glabrous style.
Conservation status: Moderately widespread. Not considered at risk.
Bean, A.R. 2004. The taxonomy and ecology of Solanum subg. Leptostemonum (Dunal) Bitter (Solanaceae) in Queensland and far north-eastern New South Wales.
Austrobaileya 6 (4): 639-816.