4. Castilleja Mutis ex L.f. (paintbrush, painted cup)

Plants annual, biennial, or perennial herbs, with fibrous roots, sometimes with woody bases, hemiparasitic, often lacking a well-developed taproot, light green to dark green, sometimes purplish-tinged, sometimes blackening upon drying. Stems solitary to several, often unbranched (branched elsewhere), erect or ascending, rounded or sometimes slightly ridged from the leaf bases, 2 of the sides sometimes slightly concave, moderately to densely grayish-pubescent with slender, weak, multicellular, nonglandular hairs, these often appearing woolly or cobwebby, sometimes wearing away in patches. Leaves alternate, sometimes also basal, sessile. Leaf blades variously shaped, entire or deeply pinnately divided or lobed into 3–7 divisions or lobes, these linear, entire along the margins, sharply pointed at the tips. Inflorescences dense, short to more commonly elongate, terminal spikes or spikelike racemes with at least the lowermost bracts more or less leafy, the median and upper bracts in some species becoming more incised and brightly colored, the flowers solitary in the axil of each bract; sessile or very short-stalked (to 2 mm in our species), lacking bractlets. Cleistogamous flowers absent. Calyces zygomorphic, tubular, strongly oblique at the tip, deeply divided into 2 primary lobes, each of these variously further lobed or divided, the lips often brightly colored (usually colored similarly to the bracts), persistent, becoming somewhat distended and papery at fruiting. Corollas 20–55 mm long, strongly bilabiate, green to yellow (red elsewhere), narrowly tubular, the upper lip fused into a slender, structure folded around the stamens, this not or only slightly hooded, tapered to an unlobed, beaklike tip, the lower lip variously well-developed or reduced, shorter than the upper one, ascending or spreading, usually 3-lobed or appearing 3-toothed, the tube straight to slightly arched, glabrous on the inner surface, the tube and lips minutely to shortly hairy on the outer surface (sometimes appearing somewhat mealy). Stamens hidden under the upper corolla lip, the filaments of 2 lengths, glabrous or hairy near the base, the anthers with 2 sacs, these unequal (1 attached near the midpoint, the other attached at its tip), blunt at the ends, yellow, glabrous. Style extended under the upper corolla lip, usually slightly exserted, the stigmatic portion capitate, unlobed or 2-lobed. Fruits (in our species) 8–17 mm long, somewhat obliquely oblong-ovoid, glabrous. Seeds variously shaped (even within a single capsule), asymmetrically oblong to oblong-ovoid or trapezoidal in outline, the outer wall loosely attached, with somewhat enlarged, translucent cells that typically lose their outer wall at maturity, the surface thus with a fine network of prominent, polygonal ridges and pits, tan to yellowish brown, orangish brown, or brown, sometimes appearing somewhat iridescent. About 190 species, North America, Central America, South America, Caribbean Islands, Europe, Asia.

At least the Missouri species of Castilleja typically have a very broad host range that includes everything from grasses to prairie forbs, and woody plants, and studies have shown that plants will even attempt to form haustoria on inert objects, such as pebbles and organic remains of dead plants (Malcolm, 1966).