Morphological comparison between Viridantha boqueronensis, V. penascoensis and V. uniflora Hern.-Cárdenas, Espejo & López-Ferr. V. uniflora A–B habit E–F, M spikes G plant with inflorescence H pistil I stamens J petals K sepals L floral bract (voucher: Hernández-Cárdenas et al. 2156, UAMIZ). V. boqueronensis C spike (voucher: K. and R. Ehlers EM7851, MEXU). V. penascoensis D spike (voucher: Hernández-Cárdenas and Sarabia 2116, UAMIZ). Photographs A–B by E. Negri Lavín; C–M by R. Hernández-Cárdenas.