Glebionis segetum (syn. Chrysanthemum segetum) is a species of the genus Glebionis, probably native only to the eastern Mediterranean region. Common names include corn marigold and corn daisy.
It is a herbaceous perennial plant growing to 80 cm tall, with spirally arranged, deeply lobed leaves 5–20 cm long. The flowers are bright yellow, produced in capitulae (flowerheads) 3.5-5.5 cm in diameter, with a ring of ray florets and a centre of disc florets.
It is widely naturalised outside of its native range, colonising western and central Europe with early human agriculture; it can be an invasive weed in some areas.
It was formerly treated in the genus Chrysanthemum, but under a recent decision of the International Code of Botanical Nomenclature, that genus has been redefined with a different circumscription to include the economically important florist's chrysanthemum.
In Gaelic, the plant was known as brenanbroi, which translates as "that which rotteth corn".
The corn marigold must have been a serious weed during the 13th century in Scotland; a law of Alexander II states if a farmer allows so much as a single plant to produce seed in amongst his crops, then he will be fined a sheep.
In Crete and Greece, the leaves and the tender shoots of a variety called neromantilida (νερομαντηλίδα) are eaten raw in salads or browned in hot olive oil by the locals.