Bidens cernua

Bidens cernua
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Asterales
Family:	Asteraceae
Subfamily:	Asteroideae
Tribe:	Heliantheae
Genus:	Bidens
Species:	B. cernua
Binomial name
Bidens cernua L.
Synonyms
Bidens ciliolata Greene Bidens cusickii Greene Bidens dentata (Nutt.) Wiegand Bidens elliptica (Wiegand) Gleason Bidens filamentosa Rydb. Bidens gracilenta Greene Bidens graveolens Komarov 1916 not Mart. 1824 Bidens kelloggii Greene Bidens leptomeria Greene Bidens leptopoda Greene Bidens lonchophylla Greene Bidens macounii Greene Bidens marginata Greene 1901 not Perr ex DC. 1836 Bidens minima Huds. Bidens prionophylla Greene Bidens quadriaristata var. dentata Nutt. Bidens tripartita var. minima Huds. Bidens venosa Gardner Buphthalmum nutans Vitman Coreopsis bidens L. Coreopsis quadricornis Krock. Coreopsis ridens Gunnerus

Bidens cernua is a plant species in the sunflower family, widespread across much of Eurasia and North America. It is commonly called nodding beggarticks or nodding bur-marigold,

Bidens cernua sometimes grows as high as 400 cm (160 inches) tall in favorable conditions. The leaves are sessile with coarsely-toothed margins. The name "cernua" means "nodding," or "hanging ." This refers to the fact that the flower heads are sometimes oriented horizontally or downwards. The plant does best in wet habitats such as swamps, marshes, and flood plains.

1796 illustration

Herbarium specimen collected in Germany

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Wikipedia