Clayweed

Clayweed, Dittrichia graveolens, is an annual herb in the family Asteraceae native to the Mediterranean basin and southwest Asia, widely naturalized as a roadside and wasteland weed in temperate regions worldwide. The common name reflects its preference for disturbed clay-rich soils along roadsides, railway embankments, field margins, and other heavily disturbed habitats. The plant is glandular-hairy throughout, producing a strong, somewhat unpleasant aromatic scent from resinous glands, which deters herbivory. Small yellow daisy-like flower heads are produced in abundance in late summer and autumn. Clayweed is a competitive colonizer of open, disturbed ground and has spread significantly along European road networks, where road-verge management, vehicle disturbance, and soil compaction create favorable conditions. It thrives in nutrient-poor, dry, often saline substrates and tolerates pollution and soil compaction. While considered a weed in many contexts, Clayweed provides late-season nectar for pollinators including hover flies, wasps, and bees at a time when few other flowering plants are available. The plant is also known as Stinking Fleabane in some references due to its smell. It is not threatened and is expanding its range in Europe as climate warming extends the growing season and road networks proliferate.