The thin, inconspicuous green flower tubes of castilleja occidentalis
are surrounded by large, yellowish green bracts, which become purple from the base when mature. Flowers have a protruding lower lip and a larger upper lip. The stems are also purplish, and woody towards the ground. The bracts, stem and leaves have a covering of long white hairs. The plant inhabits high elevation regions and is common in the tundra zone above the treeline, hence it is somewhat shorter than many other species of this widespread genus. The leaves are relatively broad at the base, unstalked, and have three distinctive lengthwise veins. Upper leaves may have two small lobes at the side, near the (pointed) tip.Castilleja flava
is somewhat similar, but its leaves are always divided.