(Ambrosia artemisiifolia L.) Fam:. Asteraceae

Danmark Bynke-Ambrosie, Estland Pujulehine ambroosia, Finland Marunatuoksukki, HollandAlsemam, Island Ömbrujurt, Lettland Vermellapu ambrozija, Litauien Kietine ambrozija, Norge Beiskambrosia, Polen Ambrozja bylicowata, Ryssland Амброзия полынолистная, Tyskland Beifußblättriges Ambrosie, Storbrittanien Malörtsambrosia


Cotyledons broadly club-shaped, apex rounded, narrowed into stalk, hairless, 5–7 mm long and 3–4 mm broad. True leaves finely divided into symmetrical lobes (ferny appearance), lobe-tip has a fine spike, sparsely hairy to hairless above, nerves whitish. Crushed leaves often aromatic. Stems erect (30–150 cm), not hollow, bluntly ridged to round, branched, the base may be slightly brownish, densly hairy. Aromatic when broken. Flower heads dioecious, inconspicuous with 10–15 pale yellow flowers in each head, spike with male flowers (produce copious amounts of pollen) at the stem tips and female flowers below at the leaf bases and in the forks of upper stems. Reproduces only by seeds (thousands!), all ragweed seeds have several small spikes so they can hitch rides on passing people and animals. Site on arable land, overgrazed pastures, gardens, uncultivated sites and ruderals. Summer annual.