Owl’s Clover
by Bruce Homer-Smith

Owl’s Clover is not a clover at all, but a kind of paintbrush. It grows in clusters, in open fields, to about 2 feet tall. Showy flowers group tightly together at the top of the stem.

Purple Owl’s Clover (Castilleja exserta) – photo © Neal Kramer

A closer look at the flower shows puffy white pouches underneath a beak. The pouches often have spots on them, giving the impression of an owl:

Dense Flower Owl’s Clover (Castilleja densiflora) - photo Keir Morse

Leaves are narrow, and often forked:

Purple Owl’s Clover (Castilleja exserta) – photo © Neal Kramer

In California, there are over 30 types of Owl’s Clover, and they often hybridize. This group is very important, because it is a larval food of the federally threatened Bay Checkerspot Butterfly.

Here’s a closer look at the flowers of two common owl’s clovers:

Dense Flower Owl’s Clover Castilleja densiflora Plant is slightly hairy. Beak curves on the back but is straight in front.

Purple Owl’s Clover Castilleja exserta ssp. exserta Whole plant is quite hairy, beak hooks over stigma

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