Bidens cernua Linnaeus
The words or terms in red
(actually dark orange) in the text are defined in a
Bidens cernua is an
annual handsome herb, often bushy,
native to North America, that is found
in swamps, bogs and other humid locations. It is highly variable.
Some botanists recognize two varieties:
var. radiata that has ray-florets
around the edge of the flower-head, and var. cernua lacking
ray-florets and producing only disk-florets,
the later one being the commoner and more widespread variety.
The plant belongs to the
In Latin, bis means twice and dens means tooth so
that bidens means two-toothed; hence the genus names refers to the
achenes of the plant,
even if these seeds have, at times, three or four bristles.
The epithet cernua is from the Latin
cernuus which means nodding, and refers to the quite often
nodding flower heads of this species, this lowered posturing occurring somewhat
more often in the literature than in nature!
Some of the vernacular names of
Bidens cernua are:
Bur marigold, Nodding Beggartick, Nodding Beggarticks,
Nodding Beggar's Ticks, Nodding Bur Marigold,
Nodding Burmarigold, Nodding Burr Marigold, Nodding Burr-marigold and
The French vernacular name is Bident penché.
The common names come from the tendency of the mature flowers to droop,
from the clinging nature of the seeds, and the superficial resemblance of the
yellow flower to the marigold. Walking through a stand of
Bidens cernua plants in late summer or autumn results
in numerous barbed nutlets adhering to the clothing.
Bidens cernua has also been known as:
- Bidens cernua L. forma discoidea
(Wimm. & Grab.) Briq. & Cavill.
- Bidens cernua L. forma minima (Huds.) Larss.
- Bidens cernua L. subvar. minima (Huds.) Coss.
- Bidens cernua L. var. dentata (Nutt.) B. Boivin
- Bidens cernua L. var. elliptica Wiegand
- Bidens cernua L. var. integra Wiegand
- Bidens cernua L. var. minima (Huds.) Pursh
- Bidens cernua L. var. oligodonta Fernald & H. St. John
- Bidens cernua L. var. radiata DC.
- Bidens cusickii Greene
- Bidens elliptica (Wiegand) Gleason
- Bidens filamentosa Rydb.
- Bidens glaucescens Greene
- Bidens gracilenta Greene
- Bidens kelloggii Greene
- Bidens leptopoda Greene
- Bidens lonchophylla Greene
- Bidens macounii Greene
- Bidens minima Huds.
- Bidens prionophylla Greene
- Bidens quadriaristata DC. var. dentata Nutt.
- Buphthalmum nutans Vitman
- Coreopsis quadricornis Krock.
Bidens are well known for taxonomic
taxonomic difficulty, the species having plastic
Bidens cernua is rather variable.
It can be identified by :
When its ray florets are missing,
Bidens cernua can be confused with Bidens connata and
Bidens tripartita; however it differs from these species by its leaves,
which are sessile
or clasp and nearly surround the stem while those of Bidens tripartita
and Bidens connata have distinct
petioles that are
winged or unwinged.
- its somewhat nodding heads with yellow showy
ligules (but they might be missing);
- its undivided simple leaves;
- its seeds that usually have 4 awns
(contradicting the Bidens genus name!)
Bidens cernua are low annuals, measuring between 1 and 4 feet in height,
often branched, with the stems sometimes rooting at the
- Linear to
- With or without teeth.
- Several per plants.
- One to two inches across.
- Erect or nodding at flowering, usually nodding in fruit.
- With up to 8 golden yellow
ray florets (but sometimes none),
about 1/2 inch long.
- With numerous orange yellow
- With and external row of 5 to 8 narrow leafy
phyllaries that have a tendency
to curl backward with age.
- With an internal row of rather broad yellow phyllaries.
- Blooming from the middle of August to the end of September in my area,
25 km north of Montréal.
- Blackish or brown cypselae,
more or less flattened;
- Measuring from 4 to 8 mm in length and about 2.5 mm wide.
- With four stiff barbed awns at the upper end.
Bidens cernua is found around ponds and lakes, along streams,
swamps, wet meadows, roadside
and railroads ditches,
and in areas of disturbed, degraded wet soils,
although it also occurs in higher quality wetlands.
Bidens cernua is found in most US States and Canadian provinces
and territories; the exceptions are Newfoundland, Labrador and Nunavut in
Canada, Florida, Mississippi and South Carolina in the USA.
It is quite common in the north-east.
The map shows the US States, Canadian provinces and territories where the plant
can be found.
It is also found in Eurasia where it is widespread.
The photos of the gallery were taken either with one of the following:
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.
- Minolta DiMAGE 7.
- Canon PowerShot A530
- Canon Xt Rebel, usually with the EF-S60mm f/2.8 Macro USM objective.
- EPSON Perfection 1650 (scanner).
The month, day and picture number might be followed by a letter:
- c for the Canon Xt Rebel.
- a for the Canon A530.
- m for the Minolta DiMAGE 7.
- s for the EPSON scanner.
Click on the thumbnails to get larger view.
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the photos shown are generally in JPEG format,
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for loading time reduction.