Hibiscus diversifolius subsp. Rivularis (Bremek. & Oberm.) Exell (Malvaceae) in Australia

Abstract

Badry, M.O., Crayn, D.M. & Tate, J.A. (2017). Hibiscus diversifolius subsp. rivularis (Bremek. & Oberm.) Exell (Malvaceae) in Australia. Austrobaileya 10(1): 113-120. Hibiscus diversifolius Jacq. is a widespread pantropical species found in Africa, Asia, Australia, and North and South America. In Australia, most populations are yellow-flowered, conforming to H. diversifolius subsp. diversifolius. However, a dark pink to maroon-flowered form previously recognized as a colour variant of subsp. diversifolius should be recognized as subsp. rivularis. After examining material from several herbaria, we find that H. diversifolius subsp. rivularis in Australia is restricted to the Atherton Tableland, north Queensland, and the remaining occurrences of the species along the east coast and in Western Australia are subsp. diversifolius. Outside Australia, subsp. rivularis is found in Africa and Brazil and the first Australian record dates to 1947. Based on this we suggest that its presence in Australia is a result of naturalisation due to one or more introductions from Africa via service personnel and/or equipment returning from the Middle East during and after World War II. A full description of H. diversifolius subsp. rivularis is provided, as are the key characters used to distinguish the two subspecies as they occur in Australia.