Inula britannica, the British yellowhead or meadow fleabane, is a plant species in the genus Inula. The plant produces the flavonol axillarin. Herbs, perennial, 10-40(-75) cm tall. Stems erect, villous. Leaves sessile; basal blades lanceolate, (3-)6-7 cm × 8-20(-30) mm; cauline blades lanceolate-elliptic to lanceolate-linear, 2-5+ cm × 5-12(-20) mm, abaxially usually densely villous and glandular, adaxially sparsely strigillose to glabrate, bases cordate or auriculate, clasping, margins entire or serrulate. Capitula 1-8, 2.5-5 cm in diam.; peduncles 1-4 cm, densely villous. Cytotoxicity-guided fractionation of the flowers of Inula britannica led to the isolation of four sesquiterpene lactones, 4 alpha, 6 alpha-dihydroxyeudesman-8 beta, 12-olide (1), ergolide (2), 8-epi-helenalin (3), and bigelovin (4). Compound 1 was isolated as a new natural product. These compounds showed cytotoxicity against human tumor cell lines.