Galinsoga quadriradiata Ruiz & Pavón

Remark The words or terms in red (actually dark orange) in the text are defined in a glossary.


july_30_17.gthmb can't be loaded. Galinsoga quadriradiata is an introduced and naturalized invasive weed in North America. It is one of the most common weeds in the United States and Canada, where it was introduced from South America. It is an annual forb that propagates is only by seeds. It has many hairy branches that bloom from July to October in my area, 25 km north of Montréal. Its chromosome number (2n) is 32.

The plant belongs to the Asteraceae family.

Name

The genus name is after Mariano Martínez de Galinsoga, 1766-1797, who was court physician and director of the Botanic Garden in Madrid. In Latin, quadra or quadrus mean square and the prefix quad means four, while radiatus means with rays (as a wheel), so that quadriradiata would mean with four rays referring to the usually five! ray florets of the flower heads ?

Common names

Some of the vernacular names of Galinsoga quadriradiata are Common Quick-weed, Fringed Quickweed, Hairy Galinsoga, Peruvian-daisy, Quick-weed and Shaggy-soldier. Its French name is Galinsoga cilié.

Synonyms

Galinsoga quadriradiata has also been known as:

Identification

Galinsoga quadriradiata is easy to identify by its small flower heads with usually five short and separated white ray florets and its numerous yellowish disk florets. It is however easy to confused it with Galinsoga parviflora which is paler green, has shorter appressed hairs while those of Galinsoga quadriradiata are spreading; furthermore the phyllaries of Galinsoga parviflora have a rounded apex instead of an acute one.

Description

Stems

Leaves

Flower heads

Fruits

Habitat

Galinsoga quadriradiata is adapted to a warm climate and heavy, nitrogen-rich and clayey soils. It is found in gardens, greenhouses, public plantations, cultivated plots, roadsides, railways and waste places, especially in and near towns and cities. These habitats are very similar to habitats in its native range, where it is also a common weed.

Distribution

Galinsoga quadriradiata is widespread in temperate and subtropic regions of the Americas and Europe; it native range covers parts of South and Central America from Mexico to Chile, but due to human activity the species has been spread far from its original range. The map shows the Canadian provinces and US states where the plant can be found. map_na.jpg can't be loaded.

Gallery

The photos of the gallery were taken either with one of the following: Minolta DiMAGE 7, Canon PowerShot A530, Canon Xt Rebel, usually with the EF-S60mm f/2.8 Macro USM objective, Fujifilm A 610 and EPSON Perfection 1650 (scanner). The title in the window shows the date when the picture was taken, i.e. jan_30_06... would mean that the photo was taken on the 30th of January, the 06 is for the 6th picture taken that day. The month, day and picture number might be followed by a letter which I use to identify the system used to take the picture.

Click on the thumbnails to get larger view. The original photos are usually in TIFF format, the photos shown are generally in JPEG format, often of dimensions one half (surface one quarter) for loading time reduction.

Plants

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Leaves

sep_02_03s.mthmb cannot be loaded. The leaves were scanned at 300 dpi; this allows to measure the dimensions of the leaves. sep_27_01s.mthmb cannot be loaded.

Flower heads

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