Herbs perennial. Roots slightly containing purple dye. Stems sparsely branched, 20-30 cm tall, densely gray-white pubescent. Leaves sessile, narrowly ovate to linear-oblong, 1-2 cm × 2-6 mm, short strigose and minutely hispid, hairs discoid at base, margin obtusely serrate, apex acute, bristly. Cymes 1.5-5 cm, several flowered; bracts same shape as leaves. Flowers heterostylous. Calyx ca. 1 cm; lobes linear, densely hirsute and hirtellous on both sides. Corolla white, yellowish when dry, tubular-campanulate, 1.5-2.2 cm, short pubescent outside; limb 5-7 mm wide, frequently purple spotted. Anthers oblong, ca. 1.6 mm. Style filiform, apex 2-lobed. Nutlets light yellow-brown, triangular-ovate, ca. 2.7 mm, tuberculate, short appressed pubescent. Fl. and fr. Jun-Sep.
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