Mentzelia perennis is a shorter, yellow-flowered species that also occurs on gypsum outcrops, but on the gypseous strata of the Yeso Formation of south-central New Mexico. Some populations of M. perennis may also have entire leaves, but they are wider (more than 4 mm) and can be basally persistent on a caespitose caudex. Mentzelia humilis is also a strong perennial that occurs on gypsum (or caliche), but in southeastern New Mexico. Its leaves are rarely entire and usually pectinate-laciniate. Mentzelia humilis has only 5 very narrow petals (about 3 mm wide) and several narrow, petal-like staminodia that quickly fade to bright white when the flowers open. Mentzelia multiflora also has pale yellow flowers (sometimes creamy white) with 10 petals, but is a biennial with branching stems; has broader, sinuate-dentate or laciniate leaves and bracts; and broader petals (more than 5 mm wide).

The scattered, discontinuous gypsum outcrops of the Todilto and Yeso formations in central and south-central New Mexico have many different forms of perennial Mentzelia that appear to be derived from introgressive crossing between M. multiflora and M. humilis. Some of these forms have not been described and lack published names. Mentzelia todiltoensis is distinctive in these taxonomically frustrating Mentzelia populations on New Mexico gypsum by possessing numerous leafy stems and long, linear leaves with relatively sparse pubescence.