Herbs, annual; hemiparasitic. Stems erect, spreading, or decumbent, not fleshy, puberulent, hispid, or villous, sometimes glandular-hairy or glabrescent. Leaves cauline, alternate; petiole absent; blade not fleshy, not leathery, margins entire or pinnately 5- or 7-lobed. Inflorescences terminal, spikes; bracts present. Pedicels absent; bracteoles absent. Flowers: sepals 2, calyx bilaterally symmetric, spathelike, lobes narrowly triangular to triangular; petals 5, corolla white, yellow, pink, or lavender, often marked or tinted with pink to purple-red lines or spots, strongly bilabiate, club-shaped, abaxial lobes 3, middle lobe erect, not revolute, adaxial 2, adaxial lip galeate, rounded at apex, opening downward; stamens 2 or 4, didynamous, filaments glabrous or sparsely pilose, pollen sacs approximate, connective not elongate; staminodes 0 or 2, peglike; ovary 2-locular, placentation axile; stigma slightly expanded at apex. Capsules: dehiscence loculicidal. Seeds 8–40, brown to dark brown, ovoid to ± reniform, wings absent. x = 7.
w United States, nw Mexico.
Species 4 (4 in the flora).
Species of Chloropyron grow almost exclusively in saline and alkaline habitats.
Chloropyron is similar to Cordylanthus and Dicranostegia and, like them, has upright flowers in which the abaxial corolla lip is usually held close to the galeate adaxial lip. The flowers appear to be in bud even when they are fully open.
T. I. Chuang and L. R. Heckard (1973) placed species of Chloropyron in Cordylanthus as subg. Hemistegia (A. Gray) Jepson. With evidence from molecular data, D. C. Tank et al. (2009) have shown that Chloropyron is closely related to Dicranostegia and that both genera form a clade that is sister to Castilleja and Triphysaria, while Cordylanthus in the narrow sense is somewhat unresolved at the base of the subtribe Castillejinae clade.
|1||Stamens 4, staminodes 0; bract margins entire or distally 2-toothed.||Chloropyron maritimum|
|1||Stamens 2, staminodes 2; bract margins pinnately lobed.||> 2|
|2||Leaf blades 1–2 mm wide, linear to linear-lanceolate; styles puberulent.||Chloropyron tecopense|
|2||Leaf blades 2–10 mm wide, narrowly lanceolate to lanceolate; styles glabrous.||> 3|
|3||Calyces 15–20 mm; seeds without abaxial crest; stems puberulent or hispid.||Chloropyron molle|
|3||Calyces 12–15 mm; seeds with abaxial crest; stems sparsely pilose or glabrescent.||Chloropyron palmatum|