Annuals; eglandular. Trichomes absent. Cauline leaves absent. Inflorescences (solitary flowers), ebracteate, not elongated in fruit. Flowers actinomorphic; sepals ascending to spreading, lateral pair not saccate basally; petals white, claw absent; filaments unappendaged, not winged; pollen 3-colpate. Fruits silicles, dehiscent, unsegmented, latiseptate; ovules 6-10(-12) per ovary; style obsolete or distinct; stigma entire. Seeds biseriate; cotyledons accumbent.

Genus 1, species 1: w North America

Despite repeated sequencing attempts and cloning of the entire ndhF gene of Idahoa scapigera (M. A. Beilstein et al. 2006 , 2008), the genus showed no affiliation to any of the other genera studied, and its systematic position remains unresolved.

Lower Taxon

• Idahoa A. Nelson & J. F. Macbride