The genus Teesdaliopsis is reduced to synonymy of Teesdalia. The new combination Teesdalia conferta is proposed. A key to the three species of Teesdalia is provided. The genus Teesdalia (2 spp.) is one of about ten genera of the Brassicaceae that have zygomorphic flowers (Rollins, 1963). It is apparently closely related to Iberis (von Hayek, 1911; Schulz, 1936). Based on Iberis conferta Lagasca, Willkomm (1880) described the monotypic section Teesdaliopsis, which was elevated to generic rank by Rothmaler (1940). According to Rothmaler, Teesdaliopsis was said to be closely related to Teesdalia but clearly differed by having 1-seeded instead of 2-seeded locules. However, Ball et al. (1993) showed that the seed number is unreliable and that only the annual vs. perennial habit can be used to separate Teesdalia and Teesdaliopsis, respectively. A critical comparison of the three species of these genera is shown in Table 1. Teesdalia and Teesdaliopsis are distinguished, respectively, by the annual vs. perennial habit and two vs. one ovule per locule. On the other hand, both Teesdalia nudicaulis and Teesdaliopsis conferta share zygomorphic flowers, and all three species share appendaged filaments and winged fruits that are extremely similar. The combination of zygomorphic flowers, appendaged filaments, and winged fruits is rare in the Brassicaceae. The differences between these two genera are so minor that Teesdaliopsis is best placed within Teesdalia. The three species of Teesdalia are separated as follows: la. Plants perennial, ovules 1 per locule T conferta (Lagasca) O. Appel lb. Plants annual, ovules 2 per locule. 2a. Basal leaf lobes obtuse, flowers zygomorphic, petals longer than sepals, stamens 6 n nudicaulis (L.) R. Brown 2b. Basal leaf lobes acute or leaves entire, flowers actinomorphic, petals not exceeding sepals, stamens usually 4 .... T coronopifolia (J. P. Bergeret) Thellung 1. Teesdalia conferta (Lagasca) O. Appel, comb. nov. Basionym: Iberis conferta Lagasca, Varied. Cienc. 2(22): 213. 1805. TYPE: no collection data (holotype, MA?). Acknowledgments. The author is indebted to Ihsan Al-Shehbaz for his support and for reviewing the manuscript.