Bidens

Scientific name

Bidens L.

Common names

water-marigold, beggarticks, stickseeds, tickseeds, tickseed sunflowers, devil's sticktight, bur-marigolds

Family

Asteraceae

Similar genera

Aciotis, Acmella, Boltonia, Eclipta, Gymnocoronis, Hypericum, Hyptis, Sphagneticola

Native distribution

cosmopolitan; mainly subtropical, tropical, and warm-temperate New World

Species cultivated

Bidens beckii Torr. ex Spreng. [syn: Megalodonta beckii (Torr. ex Spreng.) Greene.] is rarely cultivated, but may be found in specialty stores or for trade with hobbyists

these amphibiousamphibious:
(adj) of a plant able to live on land or in water
to wetland species are offered as garden ornamentals

Bidens aristosa (Michx.) Britton

B. cernua L.

B. connata Muhl. ex Willd.

B. coronata (L.) Britton [synonym of Bidens trichosperma (Michx.) Britton]

B. frondosa L.

B. laevis (L.) "Britton, Sterns & Poggenb."

B. polylepis S.F.Blake

Adventive distribution

cosmopolitancosmopolitan:
(adj) essentially worldwide in distribution

Weed status

can be weedy

Habit

amphibious amphibious:
(adj) of a plant able to live on land or in water
to emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
, sometimes floating, helophytic herbs

Brief description

Annual or perennialperennial:
(adj) (of a plant) having a life cycle of more than two years
. Stem ascending to erect, often striate. Leaves oppositeopposite:
(adj) (of leaves) two leaves per node; in pairs on opposite sides of an axis
decussatedecussate:
(adj) arranged along stem in pairs, with each pair at right angles to the pairs above and below
, sessilesessile:
(adj) attached directly, without a stalk
or petiolatepetiolate:
(adj) relating to or in the form of a petiole; bearing petioles
; leaf bladeblade:
(n) (syn. lamina) the flat, expanded part of a leaf, frond, or petal (excluding, e.g., the petiole)
simple, lobedlobed:
(adj) divided into (usually rounded) segments
, or compoundcompound:
(adj) with two or more like parts, as in a compound leaf; divided into two or more subsidiary parts or orders, as in a compound inflorescence
; margins entireentire:
(adj) having a continuous margin that is not toothed or lobed
to serrateserrate:
(adj) (of a leaf margin) bearing sharp teeth pointing forward or to the apex
when emersedemersed:
see emergent
(submerged leaves appearing whorledwhorled:
(n) bearing whorls; a type of leaf arrangement (phyllotaxis) in which leaves are in whorls
and finely dissecteddissected:
(adj) (of leaves) +/- deeply divided, cut, or lobed, including being compound
in B. beckii). Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
a terminalterminal:
(adj) at the apex
headhead:
(n) inflorescence consisting of small closely packed stalkless flowers or florets arising at the same level on a flattened axis; of several types, including: discoid (composed entirely of disk flowers) and radiate (composed of central disk flowers and marginal ray flowers)
, solitary or in cymes, pedunculatepedunculate:
(adj) borne on or possessing a peduncle
, heads usually radiate; involucreinvolucre:
(n) a whorl of bracts subtending a flower, flower cluster, or inflorescence
hemispheric; phyllariesphyllary:
(n) an individual bract of the involucre in Asteracea flower heads
biseriate. Ray florets absent or few, usually sterilesterile:
(adj) lacking male and/or female reproductive parts; not producing fruit, seed, pollen, spores, etc.
, ligulateligulate:
(adj) possessing or with a ligule
, yellow or white; disk florets bisexualbisexual:
(adj) having both male and female sexual reproductive structures on one individual or in one flower
, fertilefertile:
(adj) producing viable seed, spores, or pollen; capable of reproducing
, tube 5-lobed, yellow to orange.

Natural habitat

moist habitats, wetlands, still or slow-moving shallow water; lakes, ponds, rivers, and streams

Additional comments

Bidens contains approximately 250 species, most of which are in wetland habitats and tolerate periods of submersion. Bidens beckii (=Megalodonta beckii) is the only truly aquatic species.