The narrow leaves and stems of castilleja angustifolia
are green during moist periods but purplish when dry. Stems and leaves have a covering of short, bristly, non-glandular hairs.
Like most paintbrush species the most noticeable part of the flower head are the red bracts - modified leaves, with similar dimensions and characteristics to the leaves just below; the actual flowers are small, greenish-yellow, an inch long and tubular, projecting out just a little way at the top. Under optimum conditions the bracts are especially brilliant in color, seeming to glow from within. Bracts are divided into 3 or 5 lobes, as are the upper stem leaves. There are two varieties (var angustifolia, var flavescens); a third, var dubia, is now classed as a separate species, castilleja chromosa