Syst. Bot. 16: 658. 1991.
Herbs, annual, 0.6–6 dm; with a taproot or branched root system. Stems solitary, erect, unbranched, sometimes branched, hairs spreading, short, soft, often mixed with stipitate-glandular ones. Leaves green to purple-tinged or dark redbrown, linear-lanceolate or distal lanceolate, 2–8 (–9) cm, not fleshy, margins plane, flat to slightly curved up, 0–7-lobed, apex acute to acuminate; lobes widely spreading or ascending-spreading, linear, apex acute. Inflorescences 2.5–24 × 3–4 cm; bracts green throughout, lanceolate to ovate, 5–9-lobed; lobes ascending, linear-lanceolate or lanceolate, medium length, arising near mid length, apex acute to acuminate. Calyces green, 8–14 mm; abaxial and adaxial clefts 3–6 mm, 30–50% of calyx length, all 4 clefts subequal; lobes linear, apex acuminate to acute. Corollas straight, (15–) 20–28 mm; tube 8–24 mm; abaxial lip, beak, and proximal part of corolla-tube exserted; beak adaxially white, rarely very pale-yellow or pale pink-purple, 5–7 mm, inconspicuously puberulent; abaxial lip white, fading to pink to pink-purple, or yellow, fading to white, rarely then to pink or pink-purple, both forms often with purple or red dots at base, inflated, prominent, pouches 3, 8–10 mm wide, 4–6 mm deep, 4–6 mm, 80–100% as long as beak; teeth erect, white or yellow, 0.5 mm. Stigmas ± exserted, as long as or slightly longer than beak and visible from abaxial side. 2n = 24.
Varieties 2 (2 in the flora).
Castilleja rubicundula is separated into two varieties on the basis of flower color, as well as subtle differences in the pouching of the abaxial corolla lip. The ranges of the two varieties are broadly overlapping, but they never grow in the same location. Few intermediate forms have been recorded, though a very unusual population system exists in Santa Clara County, within which virtually all plants exhibit a tricolored corolla sequence, with yellow flowers aging to white and then pink or pink-purple, with all three colors visible on mature inflorescences.
|1||Abaxial lips of corollas white, in most populations quickly fading to pink or pink-purple.||Castilleja rubicundula var. rubicundula|
|1||Abaxial lips of corollas light to bright yellow, in some populations quickly fading to white, then rarely to pink or pink-purple.||Castilleja rubicundula var. lithospermoides|
"acute" is not a number."medium" is not a number.