As the genus name suggests, mentzelia multiflora
is a free-flowering species, often producing dozens of heads. Stems are whitish and much branched, the leaves long, narrow and lobed, the lower surface covered in short, hooked hairs. Lobes become less pronounced for leaves higher up the stem. Leaf edges are finely ciliate. The stems are also short-hairy.
The bright to pale yellow flowers measure 2 inches in diameter, and are unusual in that they are open in the afternoon and close during the morning. They are formed of five petals and five similarly-shaped but slightly shorter sepals, with rounded or blunt-pointed tips. At the center are many yellow stamens, some infertile (staminodes). Fruits are greenish, cup-shaped and about half an inch long.