Hymenoxys grandiflora is a North American species of flowering plant in the daisy family known by the common names graylocks four-nerve daisy,[2] graylocks rubberweed, or old man of the mountain.

[3] It is native to high elevations in the Rocky Mountains of the western United States.

H. grandiflora is a perennial herb up to 30 centimeters (1 foot) tall.

[4] The species has the largest flowers of any in its genus, hence the specific epithet grandiflora (large-flowered).

[4] The plant is native to high elevations in the Rocky Mountains of the western United States, in the states of Montana, Idaho, Wyoming, Utah, Colorado, and New Mexico.