Syst. Bot. 16: 656. 1991.
Herbs, annual, (0.3–)0.9–3 dm; with fibrous roots. Stems solitary or few, erect, unbranched, sometimes branched, glabrous or hairs sparse proximally, spreading, long, soft distally. Leaves green, sometimes purple-tinged, linear to narrowly lanceolate, (0.4–)1–4 cm, not fleshy, thin and flexible or thick and ± brittle, margins plane, involute, 0-lobed, apex acuminate. Inflorescences 2–15 × 2–3 cm; bracts green throughout, sometimes purplish tinged, linear to narrowly lanceolate, 0-lobed, apex acute. Calyces proximally green, pale, or purplish, distally purple or green, 5.5–11 mm; abaxial and adaxial clefts 2–5 mm, 30–50% of calyx length, deeper than laterals, lateral 1.5–2.5 mm, 25–30% of calyx length; lobes linear-lanceolate to narrowly triangular, apex acute to acuminate. Corollas straight, 11–26 mm; tube 10–22 mm; abaxial lip, beak, and part of tube exserted from calyx; beak adaxially white or yellow, 3–6 mm; abaxial lip yellow, sometimes orange, paler near teeth, prominent, deeply saccate with 3 lobes at ca. 90° from one another, pouches 6–10 mm wide, 3–4 mm deep, abruptly widening from tube, sacs ± round or ± rounded-triangular from above, villous within at base of teeth, 4–5 mm (2–4 mm from sinus), 70–90% as long as beak, puberulent; teeth erect, white, sometimes with deeply colored bases, 0.5–2 mm. 2n = 24.
Varieties 2 (2 in the flora).
Castilleja campestris is sometimes confused with Triphysaria eriantha subsp. eriantha, but C. campestris has two-celled anthers and entire leaves, while T. eriantha has one pollen sac per stamen and strongly divided leaves.
|1||Leaves and bracts linear; leaves thin, flexible; bracts shorter than or ± equal to flowers; corollas light to bright yellow; proximal pollen sacs to 1/3 length of distal.||Castilleja campestris var. campestris|
|1||Leaves and bracts lanceolate; leaves thick, ± brittle; bracts longer than flowers; corollas usually yellow to orange; proximal pollen sacs ca. 1/2 length of distal.||Castilleja campestris var. succulenta|