|Scientific Name||Bidens bipinnata|
|Common Names||English: Spanish needles; German: Fiederblättriger Zweizahn; French: Bident bipenné|
|Description||Erect annual herb, 0.1-0.9 (-1.5) m (3.93 - 35.43 (- 59.05) inch) high, belonging to the Asteraceae.|
The genus name Bidens means "two teeth", referring to the awns of the pappus and fruit (other species only have two awns). B. bipinnata is not stout and wilts when hit with direct hot sun. Ray ligules are not always present in the flower heads.
Cotyledons are petiolated and have prominent midveins, young leaves are opposite, thin with three leaflets, margins are waxy.
Petiolated, prominet midveins.
Up to +70cm (+ 27.55 inch) tall, herbaceous, erect, glabrous, 4-angled, dichotomously branching from taproot.
Opposite, petiolate, deeply bipinntifid, glabrous or with a few sparse hairs, to +/-20cm (+/-7.87 inch) long, +/-12cm (+/-4.72 inch) broad.
Petiole to 10 cm (3.93 inch) long, slightly winged. Ultimate divisions acute to acuminate.
Disk flowers typically +/-10 in number, fertile.
Ray flowers are sterile.
Corolla tube 3 mm (0.12 inch) long, 5-lobed, glabrous, orange, near and at apex.
Achenes in fruit to 1.3 cm (0.51 inch) long, blackish-green, typically unequal, with persistent pappus.
Ray flowers sterile, ligule yellow, 2-5 in number (sometimes absent), 4.5 mm (0.18 inch) long, 2 mm (0.079 inch) broad, spatulate, rounded at apex, glabrous.
Achene compressed, 1mm (0.039 inch) long, glabrous.
Single axillary pedunculate flower head.
Peduncles elongating in fruit to -10cm (- 3.93 inch) long, glabrous or sparse puberulent.
Flat fruit is crowned with two teeth or awns, which are barbed downwardly.
Main germination in spring.
Viability Of Seeds
By seed. The smooth stems persist into the early winter.
Open woods, glades, pastures, open rocky ground, thickets, waste ground, roadsides, railroads.
Clay, loam over sandstone, limestone.
Additional Crop Information
Nurseries and pastures.
Reduces trunk and canopy growth of citrus trees.
Integrated Crop Management
Prevent seed rain from the field borders and clean or mow field borders.
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