Ambrosia artemisiifoliaAmbrosia artemisiifoliaTaxonomy
Ambrosia artemisiifolia L., Sp. Pl. 2: 988. 1753
Common synonyms
Ambrosia artemisiifolia f. artemisiifolia; Ambrosia artemisiifolia subsp. artemisiifolia; Ambrosia artemisiifolia var. elatior (L.) Descourt.; Ambrosia artemisiifolia var. paniculata (Michx.); Ambrosia chilensis Hook. & Arn.; Ambrosia elata Salisb.; Ambrosia elatior L.; Ambrosia elatior var. elatior; Ambrosia glandulosa Scheele; Ambrosia monophylla (Walter) Rydb.; Ambrosia paniculata Michx.; Ambrosia paniculata f. paniculata; Ambrosia paniculata var. paniculata; Ambrosia peruviana Cabrera; Iva monophylla Walter
Common name
common ragweed, annual ragweed, low ragweed, Roman wormwood
Description
Propagule or dispersal unit is the fruit with enveloping bracts. Fertile part 2-4 mm long, 1.5-2.5 mm wide, in side view widest in upper part (obovoid), +/- straight, the upper (apical) end narrowing, in cross-section round or angular (prismatic), basal scar (carpopodium) inconspicuous and undifferentiated, central, rarely off to the side (oblique) or at least asymmetric, beak (=thinner sterile stalk between seed and pappus) absent, wings absent, propagule surface light brown or straw, wrinkled or prickly, with simple straight hairs, glands or glandular hairs, rarely no hairs (glabrous), thickened margin absent, longitudinal ribs absent.
Pappus absent.
Ecology
Annual herb. Temperate to tropical areas. Found along roadsides and watercourses, in overgrazed pastures and as a weed of crops.
Native range
North America, Central America, Carribean, South America except farthest southIntroduced range
Europe, southern Africa, China, Japan, Taiwan, Australia, New Zealand?
