Tomostima is a small genus of flowering plants in the mustard family (Brassicaceae), order Brassicales. The genus was established by the botanist Constantine Samuel Rafinesque, published in Neogenyton in 1825. It comprises approximately six accepted species of low-growing herbaceous plants distributed across the Americas, with a range spanning from northern North America south through Peru to southern South America.
As members of Brassicaceae, Tomostima species share the characteristic four-petalled flowers arranged in a cross-like pattern that gives the family its older name Cruciferae. Species in this genus were historically placed in related genera — notably Draba — before molecular and morphological studies led Al-Shehbaz, M. Koch, and Jordon-Thaden to transfer them into Tomostima. Among the accepted species are T. reptans, T. cuneifolia, T. platycarpa, T. australis, T. araboides, and T. sonorae.
Taxonomy Notes
Tomostima Raf. was published in Neogenyton (1825). Species now placed in Tomostima were long treated within Draba (Brassicaceae) and were transferred to the resurrected genus by Al-Shehbaz, M. Koch & Jordon-Thaden based on molecular phylogenetic work.
Distribution
The genus is native to Northern America (including the United States and Mexico) and South America from Peru south to the southern cone. Species occur across a wide latitudinal range in the Americas.
