This “ambrosia” came “illegally” from North America and its arrival in France is subject of controversy: for some people, it was introduced in 1863 by a batch of red clover seeds. For others, the contamination was due to U.S. aircraft that would have peddled seeds during the Second World War. In any case, its arrival in France does not date back to a century and this plant continues its invasion in the sunflower fields of the Allier and the North of Limagne. Ragweed, “Ambrosia artemisiifolia” is an annual plant, large (30 cm to 1.80 m). The stems are stout, branched, often reddish. The leaves are mostly opposite, usually lobed, with lanceolate divisions, greenish back. Flowering occurs in late summer to autumn.
The green-yellow male flower, in slender spikes, will release large amounts of pollen. The female flowers are insignificant in the axils of upper leaves.
The spiny fruits frequently cling to the hairs of animals and clothes promoting the release. Highly developed in Lyon region, ragweed was the subject of several grubbing campaigns. This plant belongs to the Asteraceae family and the genus Ambrosia has about 20 species native in America: coronopifolia ragweed, perennial with creeping rhysomes, a.trifida with 3-5 lobed leaves, Xanthium strumarium, cocklebur causing paralysis in cattle, Galinsoga parviflora and ciliata.
References: la flore d´Europe Occidentale Marjorie Blamey et Cristopher Grey-Wilson Dessin de l´artiste M.Blamey Edition Arthaud.
It has a very poetic name, but its allergenic pollen has a very high allergenicity, the main cause of hay fever, especially in America. So far, this pretty name rather evoked the food of the gods, who according to the Greeks gave them immortality, or also the aromatic plant with a citronella scent that the Jesuits had brought from Mexico... but certainly not the scourge invading the valley of the Rhone and beyond.