Boston J. Nat. Hist. 5: 255. 1845.
Herbs, annual, (0.5–)1–4.5 dm; with a taproot or branched root system. Stems solitary or few, erect, unbranched or 1–4 branches from proximal 1/2, hairs spreading, long, soft, often mixed with shorter stipitate-glandular ones. Leaves green, not forming a distinct basal rosette, sometimes relatively dense proximally with short internodes, similar in size and shape to more distal cauline leaves, narrowly lanceolate to linear-lanceolate, (1.5–)2–8(–9) cm, not fleshy, margins wavy, sometimes plane, involute, 0(–5)-lobed, apex acute; lobes erect, linear or filiform to narrowly lanceolate, apex acute to acuminate. Inflorescences 2–16(–20) × 3–5.5 cm; bracts proximally greenish, distally scarlet or bright red, sometimes deep to pale pink, peach, yellow, white, or magenta, sometimes with a white to rarely yellow medial band between green and brightly colored distal portion, proximal narrowly lanceolate, distal shorter and oblong-obovate, broadly obovate, or obtrullate, 0(–5)-lobed; lobes erect or ascending, triangular, short, arising above mid length, proximal bract apex acute, distal obtuse, rounded, or truncate. Calyces proximally light green, distally red, pale pink, or white, rarely pale yellow, usually paler than bracts, often with a white to yellow medial band between green and brightly colored distal portion, 16–31 mm; abaxial and adaxial clefts 6–10 mm, 25–33% of calyx length, deeper than laterals, lateral 0(–0.2) mm, 0(–4)% of calyx length; lobes expanded distally, apices much wider than narrow calyx tube, apex rounded, truncate, or emarginate. Corollas curved in proximal 1/3, 15–29 mm; tube 2–3.5 mm; whole corolla included or beak partly exserted, abaxial lip included; beak adaxially green, yellow, or pink, 4–10 mm; abaxial lip green, white, or yellow, reduced, pouches 3, 2 mm, 25–30% as long as beak; teeth erect, green, white, or yellow, 0.5 mm. 2n = 24.
Phenology: Flowering Jan–Jun(–Dec).
Habitat: Grasslands, pastures, dunes, oak savannas, limestone glades, open woodlands, roadsides, often in sand or clay.
Elevation: 0–400 m.
Ala., Ark., Fla., La., Okla., Tex., Mexico (Aguascalientes, Chihuahua).
Castilleja indivisa is native in Texas and adjacent states. In Mexico it is rare, with collections only from two states; these are likely waifs. This species is possibly extirpated from Arkansas. Records from Alabama (starting in 1995) and Florida (starting in 1961) are adventive populations, often on roadsides, and in some cases spreading from ornamental highway plantings. Castilleja indivisa usually has bright red bract apices and red, white, or pale pink calyx apices, but many color variants are found in nature and in cultivation, including individuals with the distal portion of the bracts colored white, pink, pale yellow, peach, or, very rarely, magenta. Uniformly white-bracted populations occur on the margins of tidal salt marshes in a small area of Nueces County, Texas, between Aransas Pass and Port Aransas. These populations likely deserve nomenclatural recognition, due to their combination of consistent coloration and unique habitat. While the main bloom period is in the spring, summer rains often allow continuing or renewed flowering during virtually any month of the year. Occasionally, plants show variation in leaf lobing; this likely reflects introgression from the C. purpurea complex, at least in some cases, such as in Coleman and McCullough counties, Texas.