Bidens bipinnata

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.

Descriptions

Characteristic Features

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.

Young Plant

Cotyledons are petiolated and have prominent midveins, young leaves are opposite, thin with three leaflets, margins are waxy.

Cotyledons

Petiolated, prominet midveins.

Stems

Up to +70cm (+ 27.55 inch) tall, herbaceous, erect, glabrous, 4-angled, dichotomously branching from taproot.

Leaves

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.

Propagatio Organs

Flowers

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.
Lobes acute.
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.
Pappus absent.
Single axillary pedunculate flower head.
Peduncles elongating in fruit to -10cm (- 3.93 inch) long, glabrous or sparse puberulent.

Flowering Period

August-October.

Fruit

Flat fruit is crowned with two teeth or awns, which are barbed downwardly.

Seeds

Main germination in spring.

Viability Of Seeds

6 years.

Propagation

By seed. The smooth stems persist into the early winter.

Occurrence

Habitat

Open woods, glades, pastures, open rocky ground, thickets, waste ground, roadsides, railroads.

Soil

Clay, loam over sandstone, limestone.

Additional Crop Information

Nurseries and pastures.

Agricultural Importance

Reduces trunk and canopy growth of citrus trees.

Control

Integrated Crop Management

Prevent seed rain from the field borders and clean or mow field borders.

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