Castilleja exserta

(A. Heller) T. I. Chuang & Heckard

Syst. Bot. 16: 657. 1991.

Common names: Purple owl’s-clover escobita
Basionym: Orthocarpus exsertus A. Heller Muhlenbergia 1: 109. 1904
Treatment appears in FNA Volume 17. Treatment on page 606. Mentioned on page 565, 570, 585, 592, 601, 602, 636.

Herbs, annual, 0.1–4.5 dm; with fibrous roots. Stems solitary, erect to ascending, unbranched or diffusely branched from near base, hairs spreading, medium length and long, stiff, mixed with short stipitate-glandular ones. Leaves green, sometimes purple to brownish, linear or ovate to orbicular in outline, (0.8–)1–5(–7.7) cm, not fleshy, margins plane, involute, (0–)3–9(–11)-lobed, sometimes with secondary lobing, apex acuminate to rounded or acute; lobes spreading, filiform or linear to narrowly spatulate, apex acute to acuminate or rounded. Inflorescences 1.5–20 × 2–4 cm; bracts proximally greenish, dark purple, brownish purple, or white, distally pink, lavender, magenta, light purple, or white on lobe apices, lanceolate to elliptic or narrowly ovate, (3–)5(–9)-lobed, often with 2–4 secondary lobes; lobes ascending to spreading, linear to filiform or narrowly spatulate, medium length to long, arising below or above mid length, apex rounded to acute. Calyces colored as bracts, 10–26 mm; abaxial clefts 4–12 mm, adaxial 9–18 mm, abaxial ca. 50% of calyx length, adaxial ca. 67% of calyx length, at least adaxial deeper than others, lateral 2.5–9 mm, 15–45% of calyx length; lobes linear (to narrowly oblanceolate), apex rounded to acute. Corollas straight, 12–33 mm; tube 7–20 mm; beak slightly exserted, hooked near apex, adaxially pink-purple to magenta, rarely white, 5–13 mm, margins colored as bracts, densely villous-hairy; abaxial lip proximally pink, purple, or magenta, rarely yellow or white, with maroon or deep purple distal to that and white to yellow or pink distally, often with purple spots, distal pale color often aging deep pink or deep red, strongly inflated, pouches 3, 3–8 mm wide, 3–4 mm deep, 3–9 mm, 67–80% as long as beak; teeth erect, white, yellow, or purple, often with purple or maroon spots, 0.5–2 mm. Filaments with spreading, long, soft hairs. 2n = 24.


Ariz., Calif., N.Mex., nw Mexico.


Varieties 3 (3 in the flora).

In addition to the characters in the key, Castilleja exserta is distinguished from the similar C. densiflora by its conspicuously hairy and apically hooked beak. As a result, the capitate stigma is exserted more or less horizontally from the corolla beak. In contrast, C. densiflora has an unhooked, inconspicuously puberulent beak, from which the stigma emerges more vertically. Castilleja exserta hybridizes with C. attenuata in southern California and with C. lineariloba in central California, and it reportedly crosses occasionally with C. densiflora in southern California.

Selected References



1 Abaxial lips of corollas deep red-purple proximally, with distal 1/4 bright yellow to yellow-orange, becoming orange or red after anthesis; w Mojave Desert, California. Castilleja exserta var. venusta
1 Abaxial lips of corollas variably colored, proximally pink to deep red-purple or white, with distal 1/4–1/3 white, yellow, or yellow-orange; widespread in Arizona and California, rare in New Mexico or limited to the coastal regions of California. > 2
2 Bracts usually less than 5 mm wide, lobes filiform to linear; inland and near-coastal grasslands and meadows; Arizona, w California, sw New Mexico. Castilleja exserta var. exserta
2 Bracts 5–7 mm wide, lobes linear to narrowly spatulate; coastal dunes and bluffs; California. Castilleja exserta var. latifolia
... more about "Castilleja exserta"
J. Mark Egger +, Peter F. Zika +, Barbara L. Wilson +, Richard E. Brainerd +  and Nick Otting +
(A. Heller) T. I. Chuang & Heckard +
Orthocarpus exsertus +
Purple owl’s-clover +  and escobita +
Ariz. +, Calif. +, N.Mex. +  and nw Mexico. +
Euchroma +  and Oncorhynchus +
Castilleja exserta +
Castilleja +
species +