UNEXPECTED DIVERSITY OF AUSTRALIAN TOBACCO SPECIES (NICOTIANA SECTION SUAVEOLENTES, SOLANACEAE) Mark W. Chase, Maarten J. M. Christenhusz, John G. Conran, Steven Dodsworth, Felipe Nollet Medeiros de Assis, Leonardo P. Felix and Michael F. Fay Summary. This special issue highlights some of the wonderful species of native Australian tobacco (Nicotiana sect. Suaveolentes ). We here present twelve species of this genus, four of which are new to science. Many Nico- tiana species have a high ornamental value, and we hope that particu- larly the rarer Australian species will fnd a way into horticulture to pre- vent them from becoming threatened. This would allow maintenance of ex-situ populations, mitigating the effects of changing climate and intro- duction of invasive species. Tobaccos dispersed into the Australian out- back around two million years ago and are now radiating there. It has been clear that they have interesting cytological evolution as well as morpholog- ical differences. They appear to have peculiar drought adaptations, which are needed for thin-leaved herbs growing in some of the driest places on the planet. Introduction Nicotiana L. is the ffth largest genus of Solanaceae, after Solanum L., Lycianthes (Dunal) Hassl., Cestrum L. and Nolana L.f. (Chris- tenhusz et al., 2017). It was previously in seventh place, but with many recent discoveries, including the species described in this issue, it moves ahead of Physalis L. and Lycium L. Within Solanaceae, the genus is a member of Nicotianoidae (Olmstead et al., 1999), which also include the Australian Anthocercideae: 31 species in seven genera, the largest genus being Anthocercis Labill. with 11 species (Fig. 1 A, B), followed by Duboisia R.Br. with only four species (Fig. 1 C, D). This subfamily is sister to Solanoideae (Särkinen et al., 2013) and shares with them the base chromosome number of n = 12 (Olmstead et al., 1999). Nicotiana was named for Jean Nicot (1530–1600), French scholar, diplomat and the person who frst brought tobacco plants from Portugal to the French Royal court, promoting it as a medicinal plant. It is of course a commercially important genus, with the allotetraploid species, Nicotiana tabacum L. (Fig. 2), being the most important cultivated species of the Curtis’s Botanical Magazine 2018 vol. 35 (3): pp. 212–227 212 © The Board of Trustees of the Royal Botanic Gardens, Kew 2018.