Calylophus berlandieri Spach subsp. pinifolius (Engelmann ex A. Gray) Towner; Meriolix hillii Small; M. melanoglottis Rydberg; M. serrulata (Nuttall) Walpers var. pinifolia (Engelmann ex A. Gray) Small; Oenothera berlandieri (Spach) Steudel subsp. pinifolia (Engelmann ex A. Gray) W. L. Wagner & Hoch; O. serrulata Nuttall var. maculata H. Léveillé; O. serrulata subsp. pinifolia (Engelmann ex A. Gray) Munz; O. serrulata Nuttall var. pinifolia Engelmann ex A. Gray

Herbs annual or short-lived perennial. Stems 1–several, unbranched or sparsely branched, ascending to erect, 30–80 cm. Leaves 2.5–9 × 0.2–1 cm; blade margins remotely serrulate to spinulose-serrate. Flowers: buds with free tips 0.5–4 mm; sepals with conspicuously keeled midribs. 2n = 14.

Flowering Mar–Sep. Prairies, open places in oak savannas on rocky, clay, or sandy soil, often calcareous; 0–900 m; La., Okla., Tex.

Subspecies capillifolia occurs from Blaine and Lincoln counties, Oklahoma, south through a narrow portion of north-central Texas to central Texas, where it is widely distributed, especially on the Edwards Plateau; also occurring locally in western and southern Louisiana. The floral tubes and/or stigma of some populations, especially from Bexar, Blanco, Comal, Gillespie, Hays, Kendall, Kerr, and Travis counties, Texas, are a deep blackish purple, while others are yellow, which is typical of the section.