Linaria vulgaris is a species of toadflax (Linaria), native to most of Europe and northern Asia, from the United Kingdom south to Spain in the west, and east to eastern Siberia and western China. It is a perennial plant with short spreading roots, erect to decumbent stems 15–90 cm high, with fine, threadlike, glaucous blue-green leaves 2–6 cm long and 1–5 mm broad. The flowers are similar to those of the snapdragon, 25–33 mm long, pale yellow except for the lower tip which is orange, borne in dense terminal racemes from mid summer to mid autumn.

A new alkaloid, 1,2,3,9-tetrahydropyrrolo(2,1-b)quinazolin-1-carboxylic acid (1), together with eight known compounds, 7-hydroxy vasicine (2), benzyl alcohol beta-D-(2'-O-beta-xylopyranosyl)glucopyranoside (3), benzyl alcohol O-beta-D-glucopyranoside (4), benzyl alcohol O-beta-D-primveroside (5), 3,5-dimethyl-4-hydroxy benzaldehyde (6), gluco-syringic acid (7), syringin (8), and liriodendrin (9), were isolated from the plants of Linaria vulgaris.