Dittrichia

Dittrichia is a small genus of flowering plants in the family Asteraceae. The best known species is Dittrichia viscosa, commonly called yellow fleabane or sticky fleabane, native to the Mediterranean region. The genus comprises a few related species, most of which occur in the Mediterranean and surrounding areas. In some classifications, Dittrichia viscosa has also been treated as Inula viscosa, reflecting historical changes in its placement within the tribe Astereae of Asteraceae.

Morphology and description

Plants are herbaceous perennials or annuals that can reach up to about one to two meters in height. They typically have erect stems with a sticky, aromatic or resinous surface. Leaves are opposite, simple, lanceolate to oblanceolate, and often serrated, sometimes with a rough or hairy texture. The flower heads are bright yellow and arranged in dense clusters at the ends of branches. Each head contains both ray and disc florets, a characteristic of many Asteraceae. Flowers bloom in summer to autumn, attracting a variety of pollinators. The fruit is achenes with a light, wind-dispersed pappus.

Distribution and habitat

Dittrichia species are native to the Mediterranean basin and adjacent regions in Europe, North Africa, and western Asia. They favor dry, sunny habitats such as garigue, rocky slopes, open woodlands, and disturbed areas, and some species have become naturalized beyond their native range.

Ecology and uses

The plants produce aromatic oils and can emit a strong odor when crushed. This scent has given rise to common names in various languages. They are valued by pollinators for their bright yellow flowers in summer. Some species have become weedy or invasive in regions where they have been introduced, particularly in Mediterranean-type climates.

Taxonomy

Dittrichia belongs to the Asteraceae and has historically been grouped with related genera such as Inula. The taxonomic placement, species circumscription, and names have varied with different floras and revisions.