Lygodesmia exigua Prenanthella is a monotypic genus of flowering plants in the family Asteraceae.

[1] It contains the single species Prenanthella exigua, which is known by the common name brightwhite.

[2] It is native to the southwestern United States from California to Texas and it is known as far north as Idaho.

This annual herb produces a slender, branching stem reaching a maximum height near 40 centimeters.

Each small head is cylindrical and narrow, its base wrapped in lance-shaped phyllaries.