It is endemic to California, where it is known from the North Coast Ranges to the southern Central Valley, San Joaquin Valley, and Sierra Nevada foothills.

It is a member of grassland and woodland plant communities.

Pentachaeta exilis is an annual herb with a hairy stem no more than about 6 centimeters tall.

The narrow linear leaves are up to 3 centimeters long but only about a millimeter wide.

The rare subspecies aeolica, which is known from just a few occurrences in the Central Coast Ranges, generally produces some white ray florets around a center of yellow disc florets.