Hairy owl clover (Castilleja tenuis) is a small plant found in vernally (springtime) moist flats and meadows as well as other damp sites in the Pacific states, Idaho, Nevada and British Columbia. Members of the Castilleja genus are also known as paintbrushes. Paintbrushes as a group are easy to recognize, however individual species are difficult to identify.
An annual native, hairy owl clover is what can be termed a pygmy flower – very small and almost inconspicuous. Hairy throughout, the alternate stem leaves are narrow and linear lower on the stem while the upper leaves may have one or two pair of lobes. The terminal flowers barely extend beyond the bracts (specialized leaf associated with the flower). Like other members of the snapdragon family, hairy owl clover has five petals united into a two-lipped corolla. The lower lip is inflated with three sacs while the upper lip is straight and extends a couple millimeters beyond the lower lip. These flowers, photographed near Crystal Lake (Shasta County CA), are yellow, but hairy owl clover can also be an off-white color.
Paintbrushes can be eaten and were used medicinally in the past. Care must be taken though with members of Castilleja because they accumulate selenium, a potentially toxic element, in areas of selenium rich soils. Because hairy owl clover is such a small plant and because of potential toxicity, this paintbrush should probably not be utilized for culinary or other purposes.
A former name for C. tenuis that is still seen in the literature is Orthocarpus hispidus. Colloquially, hairy owl clover is also known as hairy Indian paintbrush and annual white paintbrush.