''Erigeron bonariensis'' is a species in the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

, found throughout the tropics and subtropics as a pioneer plant; its precise origin is unknown, but most likely it stems from

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. It has become naturalized in many other regions, including

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. Common names of ''E. bonariensis'' include flax-leaf fleabane, wavy-leaf fleabane, Argentine fleabane, hairy horseweed, asthma weed and hairy fleabane.

Description

''Erigeron bonariensis'' grows up to in height and its leaves are covered with stiff hairs, including long hairs near the apex of the

bract In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

s. Its

flower heads A pseudanthium (; : pseudanthia) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, composite flowers ...

have white

ray florets Asteraceae () is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger fa ...

and yellow

disc floret Asteraceae () is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger fa ...

s. It can easily be confused with '' Erigeron canadensis'', which grows taller, and '' E. sumatrensis''. It flowers in August and continues fruiting until the first frosts. It is instantly recognisable by its blue-green foliage, very narrow, undulate stem-leaves, and purple-tipped involucral bracts. It reproduces only by seed, which are easily blown and spread by wind.

Distribution and habitat

''Erigeron bonariensis'' is found throughout the tropics and subtropics as a pioneer plant; its precise origin is unknown, but most likely it stems from

. It has become naturalized in many other regions, including

and

. ''E. bonariensis'' is a rare alien in southeastern

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

, found along walls and in cracks in pavements and concrete

driveway A driveway (also called ''drive'' in UK English) is a private road for local access to one or a small group of structures owned and maintained by an individual or group. Driveways rarely have traffic lights, but some may if they handle heavy ...

s. It is widespread throughout Australia, where it thrives on roadsides,

fallow Fallow is a farming technique in which arable land is left without sowing for one or more vegetative cycles. The goal of fallowing is to allow the land to recover and store Organic compound, organic matter while retaining moisture and disrupting ...

pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Types of pasture Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, c ...

s, gardens, lawns,

footpath A footpath (also pedestrian way, walking trail, nature trail) is a type of thoroughfare that is intended for use only by pedestrians and not other forms of traffic such as Motor vehicle, motorized vehicles, bicycles and horseback, horses. They ...

s, parks,

riparian A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...

vegetation, forest and

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

perimeters, waste dumps and disturbed grounds.

Brisbane City Council Brisbane City Council (BCC, also known as Council) is the local government of the City of Brisbane, the capital city of the Australian state of Queensland. The largest local government in Australia by population, BCC's jurisdiction includes 2 ...

Weed Identification Tool

Photographic Description

Dry Summer Form

*The following are bright dry summer 1st-year forms; in contrast to shady damp winter forms that follow. Erigeron bonariensis from Antalya by D Merrick 11.jpg, General view Erigeron bonariensis from Antalya by D Merrick 09.jpg, Top-heavy greyish gangly look with initial central inflorescence subsequently overtopped by some side ones Erigeron bonariensis from Antalya by D Merrick 01.jpg, Broad heads (may be narrower especially in winter) usually with reddened tips Erigeron bonariensis from Antalya by D Merrick 02.jpg, Head close up Erigeron bonariensis from Antalya by D Merrick 05.jpg, Leaf narrow showing hairs Erigeron bonariensis from Antalya by D Merrick 07.jpg, Leaf surface hairs (similar underside), sometimes poorly hairy Erigeron bonariensis from Antalya by D Merrick 06.jpg, Hairs at leaf tip Erigeron bonariensis from Antalya by D Merrick 08.jpg, Leaf base hairs (a few long ones usually present) and underside hairs Erigeron bonariensis from Antalya by D Merrick 10.jpg, Stem leaves of robust stems multi-lengthed, grey (sometimes green)

Winter, Damp, Shady, Biennial Forms

*Showing diffusely branched or strangled appearances with small flower heads Erigeron bonariensis from Antalya by D Merrick 101.jpg, Winter form near water in the open Erigeron bonariensis from Antalya by D Merrick 102.jpg, Strangled winter form in the open Erigeron bonariensis from Antalya by D Merrick 103.jpg, Winter form in damp shade Erigeron bonariensis from Antalya by D Merrick 108.jpg, From a biennial form Erigeron bonariensis from Antalya by D Merrick 03.jpg, May have particularly reddened heads

Other photos

Erigeron bonariensis1.jpg, Erigeron bonariensis growing as a weed on a building in New Delhi, India Conyza bonariensis stem1 & sumatrensis stems (12402804144).jpg, Stiff hairs cover the plant. Starr-170304-0326-Conyza bonariensis-leaves-Lower Waiohuli Trail Polipoli-Maui (33382595585).jpg, Basal rosette leaves, before plant matures and flowers,

Maui, Hawaii Maui (; Hawaiian language, Hawaiian: ) is the second largest island in the Hawaiian archipelago, at 727.2 square miles (1,883 km2). It is the List of islands of the United States by area, 17th-largest in the United States. Maui is one of ...

Conyza bonariensis.jpg, Foliage becomes grey-green in dry-summer regions, such as Israel Starr-170225-0052-Conyza bonariensis-flowers-Lower Waiohuli Trail Polipoli-Maui (32566847513).jpg, White ray flowers and yellow disc flowers in fully "open" flower heads, Maui, Hawaii Erigeron bonariensis (Familyː Asteraceae) - weed.jpg, Flower heads are followed by seeds, which are easily carried by the wind.

References

{{Taxonbar, from1=Q21874195, from2=Q2453589 bonariensis Flora of Southern America Plants described in 1753 Taxa named by Carl Linnaeus