Plagiobothrys tenellus is a species of flowering plant in the borage family known by the common names Pacific popcornflower and slender popcornflower.

It is native to western North America from British Columbia to Mexico, where it is a common member of the flora in several types of habitat.

Plagiobothrys tenellus is an annual herb producing several erect stems up to about 30 centimeters tall.

The inflorescence is a coiling branch bearing many small five-lobed white flowers.

The fruit is a tiny cross-shaped nutlet covered in bumps and grooves.