It is found in California coastal sage and chaparral habitats on the islands.

Dendromecon harfordii is a shrub or small tree reaching heights between 2–6 metres (6.6–19.7 ft).

It has thin branching stems covered sparsely in smooth-edged, oval-shaped leaves 3 to 8 centimeters long.

It bears showy flowers with four bright yellow petals each 2 or 3 centimeters long.

The fruit is a curved, cylindrical capsule over 7 centimeters in length.