Herbs annual, erect, 35--75 cm tall, glabrous throughout. Stems straw-colored when dry, terete, often branched only in inflorescences. Leaves opposite, sessile or subsessile, ovate-lanceolate, 4--10 X 1.2--3.2 cm, sparsely dark purple or black glandular punctate and striate, especially near margin, base rounded, apex caudate-acuminate; veins 4 or 5 pairs; veinlets inconspicuous. Racemes terminal, laxly axillary, 4--11-flowered; peduncle 6--12 cm; bracts subulate, 3--5 mm. Pedicel filiform, 1--3 cm, usually divaricate. Calyx lobes lanceolate, 5--7 X 1.2--1.5 mm, dark glandular punctate, narrowly hyaline margined. Corolla yellow, 1.2--1.5 cm in diam.; tube 1.5--2 mm; lobes rhomboid-ovate to narrowly oblong, ca. 5 X 3--4 mm, sparsely dark purple glandular striate near apex, apex acute. Filaments connate basally into a 2--2.5 mm high ring, free parts 1.5--3.5 mm; anthers narrowly oblong, dorsifixed, opening by lateral slits, ca. 1.2 mm. Ovary ovoid; style 5--6 mm. Capsule subglobose, 3--3.5 mm in diam. Fl. May-Jun.
Home