It is a found below 700 metres (2,300 ft) in chaparral, oak woodland, and coastal prairie habitats.

[1] Leptosiphon acicularis is an annual herb producing a hairy stem no more than about 15 centimeters tall.

The oppositely arranged leaves are each divided into very narrow bristlelike lobes up to a centimeter long.

The tip of the stem has an inflorescence of one or more tiny yellow flowers surrounded by many needlelike sepals.

The specific epithet, acicularis, is derived from Latin and means "needle-shaped".