Description from Flora of China
Buglossoides arvensis (Linnaeus) I. M. Johnston; Rhytispermum arvense (Linnaeus) Link.
Herbs annual. Roots with purple dye. Stems usually single, branched from base or only above, 15-30 cm tall, short strigose. Leaf blade oblanceolate to linear, 2-4 cm × 3-7 mm, short strigose, apex acute. Cymes terminal, to 10 cm; bracts same shape as leaves but smaller. Flowers sparse, short pedicellate. Calyx lobes usually erect, linear, 4-5.5 mm, to 1.1 cm in fruit, short strigose on both sides, base becoming slightly hardened. Corolla white, sometimes blue or light blue, salverform; tube ca. 4 mm, sparsely pubescent outside; throat with 5 bands of hair extending to tube; limb ca. 1/2 as long as tube; lobes somewhat unequal, erect to slightly spreading, ovate or oblong, ca. 1.5 mm. Stamens attached below middle of tube; anthers oblong, ca. 1 mm. Style 1.5-2 mm; stigma capitate. Nutlets gray-brown, triangular-ovoid, ca. 3 mm, finely tuberculate. Fl. and fr. Apr-Aug. 2n = 14, 28, 36, 42.
A highly variable species with several infraspecific taxa recognized in Europe.
Hills, pastures, mountain slopes, margins of cultivated ground. Anhui, Gansu, Hebei, Heilongjiang, Hubei, Jiangsu, Jilin, Liaoning, Shaanxi, Shandong, Shanxi, Xinjiang, Zhejiang [Afghanistan, N India, Japan, Kashmir, Kazakhstan, Korea, Kyrgyzstan, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; SW Asia, Europe]