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 Add this item to the list   Ambrosia artemisiifolia


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 Vernacular names:Alsemambrosia (NL), Ragweed (UK) 
 Synonyms:Ambrosia artemisiifola var. elatior (L.) Descourtilz, Ambrosia artemisiifolia var. paniculata (Michaux) Blankinship, Ambrosia elatior L., Ambrosia glandulosa Scheele, Ambrosia media *, Ambrosia monophylla (Walter) Rydberg 
 Plant code - standard list:FB0048 
 Botanical thesaurus:
 Factsheet link (English):
 Factsheet link (French):
 Factsheet link (Dutch):


 Height of plant (m):0.3 - 1 
Roots and stem
 Description of subterranean parts:shallow, fibrous root system. 
 Description of stem:erect, hairy, sulcate, with several branches above. 
Fruit and seeds
 Description of seed:seed is enclosed in a hard, ridged and woody achene-like (bur) fruit. 
 Description of fruit:a bur: a hard, ridged and woody achene-like fruit, 2-5 mm long, including a subulate beak 1.5-2 mm, and with 5-7 spines, yellowish to reddish-brown. 
 Length of fruit (mm):2 - 5 
 Width of fruit (mm):1.5 - 2.5 
 Number of propagules per plant:3000 - 32000 
 Description of leaf:1-2 pinnatifid, ovate in outline, dark green, appresed-hairy above, grey-felted beneath. 
 Length of petiole (cm):2.5 - 6 
alternate yes
opposite yes
decussate no
whorled no
 Description of inflorescence:staminate flowers (tubular) in capita, numbering 10-200 per plant, short stalked, without pappus, heads 4-5 mm in diameter, 10-15 flowered, hemi-spherical, phyllaries 5-12, united below, smooth or a little hairy, herbaceous, drooping in clusters at the end of branches in terminal, leafless racemes. Pistillate flowers (tubular) also in capita, without pappus, single of clusters of 2-4 are located in leaf and branch axils, heads 4-5 mm in diameter, phyllaries 5-12, united below. Gender variation may range from completely female to nearly 78% male. 
 Description of flower:? heads,10-15 flowered, enclosed by proximally fused phyllaries (smooth or little hairy). ? heads with only 1 flower (without corolla), enclosed by almost fused phyllaries becoming hard and woody and bearing a subulate beak (1.5-2 mm) and 5-7 spines. 
Colour of flower:
white variable
yellow variable
orange no
pink no
brown no
red no
purple no
blue no
green no
 Description of stamens:anthers yellow, almost free. 
 Description of ovary:1-celled with 1 ovule, inferior. 

Additional information

 Uses:A. artemisiifolia may be used for phytoremediation of soils contaminated with metals, and as an anti-inflammatory agent and as an antibacterial agent. 
 Similar species:Ambrosia psilostachya DC. is very similar in appearance to A. artemisiifolia except that the former is a perennial with horizontal creeping roots whereas the later is an annual with a tap root. Moreover, leaves of A. psilostachya are more greyish green and not as finely divided, the phyllaries of male flowers are roughly hairy and the fruits are smaller, have a beak of ca 1.5 mm and 0-4 blunt spines. 
 Look-alike link:

Distribution information

 Original distribution:is native to North America and originated in south-eastern USA. 
 Current distribution:Asia: Azerbaijan, China, India, Japan, Kazakhstan, Korea Republic of, Turkey. Europe: Austria, Belgium, Croatia, Czech republic, France, Germany, Hungary, Italy, Lithuania, Luxembourg, Macedonia, Moldova, Netherlands, Poland, Portugal, Madeira, Romania, Russian Federation, Serbia and Montenegro, Slovakia, Spain, Sweden, Switzerland, Ukraine, UK. Africa: Mauritius, South Africa. North America: Bermuda, Canada, Mexico, USA. Central America: Cuba, Guadeloupe, Guatemala, Jamaica, Martinique. South America: Argentina, Bolivia, Brazil, Chile, Colombia, Paraguay, Peru, Uruguay. Oceania: Australia, New Zealand. 
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Biochemistry and molecular data

 Ploidy:2n = 34, 36. 


Life cycle:
annual yes
perennial no
monocarp no
biennial no
 Competitiveness:ragweed plants have an allelopathic influence on crops. 
Flowering time in Europe:
January no
February no
March no
April no
May no
June no
July no
August no
September yes
October yes
November no
December no
 Pollination characteristics:male flowers produce excessive wind dispersed pollen. 
 Hardiness:not resistant to frost. 
 Dormancy:the plant produces large numbers of dormant seed in autumn able to survive for up to 40 years in soil; a portion of the seeds germinate in spring (there was large variation by site in the proportion, while the rest of the seeds enter secondary dormancy. Large differences in seed density of the seed banks between sites were mostly explained by the type of habitat; these suggest that the invasion potential of A. artemisiifolia is closely related to persistent soil seed bank and how this is affected by processes in different habitats. 
 Habitat requirements:seeds of A. artemisiifolia can only germinate on disturbed ground where natural grasses are absent. It grows in sandy or clay soils, but grows well on wet, heavy soils at pH 6.0-7.0, but is susceptible to frost. 
 Ecological amplitude:a weed found along roadsides and in pastures, wasteland, canals, orchards, field margins, nurseries etc. 
 Habitat elsewhere:on open, dry wastelands. 
 Habitat in the Netherlands:on open, dry wastelands. 
 Palatability:pigs and sheep will consume A. artemisiifolia, cattle may eat this weed after grasses have been exhaused but this changes the flavour of the milk producing an undesirable product and these cattle may also suffer nausea; the fruits are often eaten by small birds and animals. 

Invasiveness, risk and control

Dispersal mechanism:
wind variable
water variable
others ?
endozoochorous ?
ectozoochorous ?
 Invasive behavior information:A. artemisiifolia is a very aggressive and competitive weed in several crops and may also serve as an alternative host for crop diseases; it can violate the biological diversity of species and may be destructive to flora. See also : Palatability. 
 Toxicity:its pollen is an important allergen, threatening human health. 
 Control:a combination of crop rotations, mechanical cutting and chemical treatment can help to control (absence of selective herbicide for control!). It may soon bee possible to detect dense populations of ragweed using spatial remote sensing methods; gamma irradiated treatment of 30 krad can kill A. artemisiifolia. 
 Pathway of introduction:fruits are are commonly found in stored and transported grains, wool and as a contaminant of bird seed. 

Link to other websites / databases

 Link to other websites_Url: