Trifolium macrocephalum is a rhizomatous perennial herb taking an upright form. The herbage is hairy. The leaves are made up of five or six thick oval leaflets each measuring up to 2.5 centimeters in length and have short teeth at their margins and often a pale transverse mark.
The inflorescence is crowded, egg-shaped and up to 5 or 6 centimeters long. Each flower has a calyx of sepals with lobes narrowing into bristles which are coated in long woolly hairs. The flower corolla may be nearly 3 cm in length and is pink to lavender in color, or sometimes bicolored. It blooms early in spring. As both the Latin and common names suggest, the flower head is unusually large for a clover.
Trifolium macrocephalum is native to the Great Basin region of the western United States, from Washington to northern California, and Nevada to Idaho. It occurs in several types of habitat, including sagebrush scrub, juniper woodland, yellow pine forest, and mountain woodlands. It prefers thin-soiled, rocky areas.