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Annual bur-sage

Invasive Species Information

Biodiversity Medium Risk 17

What Is Annual bur-sage - (Ambrosia artemisiifoIia)?

Habitat: Terrestrial
Distribution in Ireland:

Status: Established

Family name: Asteraceae

Common name/s: Ragweed, common ragweed

Reproduction: Characteristic flower head composed of numerous individual sessile flowers. The flower head consists of male flowers, while female flowers are located solitarily or in small groups with male and female owers in the same plant.

Biodiversity Medium Risk 17

Annual bur-sage flowers

Common ragweed germinates in the spring (April) and grows rapidly during the juvenile phase under optimum condition promoting the competitive ability of the plant.  

Biodiversity Medium Risk 17

Ambrosia acanthicarpa is a North American species of bristly annual plants in the sunflower family. Members of the Ambrosia genus are called ragweeds.

 

The species has common names including flatspine bur ragweed, Hooker's bur-ragweed, annual burrweed, and annual bur-sage, and western sand-bur. The plant is common across much of the western United States and in the three Prairie Provinces of Canada.

Annual bur-sage stem and leaves

Annual bur-sage is a spiny, weedy plant growing in clumps of many upright stems which can reach over a meter in height. Grey-green stems are covered in stiff, bristly hairs.

 

Rough leaves are several centimeters long. The plant has numerous racemes of flowers with each hairy flower head a few millimeters wide.

 

Spiny, burr-like pistillate heads have pointed, twisting bracts and the staminate heads are rounded. The species is adaptable and grows well in disturbed areas, easily becoming weedy.

How To Identify Annual bur-sage?

Biodiversity Medium Risk 17

ID Guide

Leaf: Fernlike - toothed leaves 4-10 cm long. Bright green on both sides with whitish nerves. Lower leaves arranged oppositely, with upper leaves often arranged alternately on the stem of mature plants.  
Flower: Female flowers are solitarily or in small groups located at the base of upper leaves. Male flowers are small and green (2-4 mm) grouped in spike-like flower heads (racemes) at the end of the upper branches. 
Stem: Reddish, hairy with a diameter of up to 2-4 cm at the base. 
Fruit: Single seeded, red-dish-brown fruit (achenes), 3-4 mm long.

Biodiversity Medium Risk 17

Annual bur-sage

Biodiversity Medium Risk 17

Annual bur-sage

Biodiversity Medium Risk 17

Annual bur-sage seeds

Biodiversity Medium Risk 17

Annual bur-sage leaf

Biodiversity Medium Risk 17

Annual bur-sage flower

Why Is Annual bur-sage A Problem?

Annual bur-sage is an alien (non-native) invasive plant, meaning it out-competes crowds-out and displaces beneficial native plants that have been naturally growing in Ireland for centuries.

 

Annual sage-bur represents a very serious health risk for humans as pollen-allergenic plant. Pollen of ragweed is among the most potent triggers of hay fever and allergic rhinitis. In addition to allergic rhinitis, ragweed allergy often causes severe asthma-like symptoms. In Europe- and countries with large ragweed populations 10-20% of patients with pollen allergy symptoms suffer from ragweed- allergy. 

Effect on biodiversity and recreation. Dense growth of common ragweed may lead to out-shading of existing vegetation and may be a threat to native species especially after a disturbance such as overgrazing which put competitive pressures on the native flora.

 

Annual sage-bur can also cause illness in livestock that ingest it and causes problems for the conservation and management of pastures. 

European Communities (Birds and Natural Habitats) Regulations 2011 non-native invasive plant species A-Z (Updated 2017)

There are currently 35 invasive plant species listed in the European Communities (Birds and Natural Habitats) Regulations (annex 2, Part 1)...

 

Click on a species from the following list to find out more regarding non-native species subject to restrictions under Regulations 49 and 50.

Additional Non-Native Plant Species identified as Medium Risk on Ireland's Biodiversity List...

Common name 

African woodsorrel

American skunk cabbage

Annual bur-sage

Antithamnionella ternifolia

Barberry

Black currant

Brazilian waterweed

Butterfly-bush

Canadian-fleabane

Clover broomrape

Creeping Bellflower

Dead man's fingers

Douglas fir

Early goldenrod

False acacia

Field penny-cress

Garden lupin

Giant rhubarb

Hairy rocket

Himalayan honeysuckle

Himalayan knotweed

Holm oak

Japanese barberry

Japanese honeysuckle

Japanese rose

Leafy spurge

Least duckweed

Narrow-leaved ragwort

New Zealand bur

Ostrich fern

Pampas grass

Pitcherplant

Red oak

Red sheath tunicate

Rock cotoneaster

Rum cherry

Russian-vine

Salmonberry

Sea-buckthorn

Sycamore

Three-cornered garlic

Traveler's-joy

Tree of heaven

Turkey oak

Virginia-creeper

Warty cabbage

Water fern

Wild parsnip

Environment 

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Freshwater 

Terrestrial 

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Terrestrial 

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Marine 

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Terrestrial 

Terrestrial 

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Risk score 

14

15

17

15

14

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17

17

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17

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14

17

17

17

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17

14

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14

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14

14

14

14

14

14

14

17

14

14

14

15

15

17

17

14

16

15

14

15