Bidens bipinnata

Bidens bipinnata
photo by Gil Nelson
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta - Flowering plants
Class:	Magnoliopsida - Dicotyledons
Order:	Asterales
Family:	Asteraceae ⁄ Compositae
Genus:	Bidens
Species:	B. bipinnata
Binomial name
Bidens bipinnata L.
Natural range of Bidens bipinnata from USDA NRCS Plants Database.

Common name: Spanish needles

Taxonomic notes

Synonym: Bidens bipinnata var. bipinnata

Description

A description of Bidens bipinnata is provided in The Flora of North America.

B. bipinnata is an annual herb. It tends to be a ruderal, weedy species.

Ecology

Habitat

B. bipinnata is found in marsh and island communities, river bluffs, and pine-oak woodlands. It has also been found in disturbed areas including campgrounds, roadsides, ditches, disturbed coastal hammocks, old fields, and fire line. This species prefers shaded environments and moist sandy soil types like sandy loam, red sandy clay, and loamy sand.

Associated species includes Quercus geminata, Desmodium ochroleucum, D. rotundifolium, Pinus, other Quercus's, Cornus florida, Liquidambar styraciflua, and others.

Phenology

This species has been observed flowering and fruiting from July to October.

Seed dispersal

The barbed awns of the seeds allow for the seed to attach to animals and humans and be dispersed far distances.

Fire ecology

B. bipinnata is a seeder; 70% mortality when subjected to 100% leaf scorch. It is fire tolerant and frequent in firebreaks.

Use by animals

Caterpillars of moths Cirrhophanus triangulifer, Condica confederata, Epiblema otiosana, Palthis asopialis, Platysenta mobilis, and Synchlora aerata feed on the foliage. Leaf beetles Calligrapha bidenticola and Calligrapha californica feed on the leaves. The aphid Aphis coreopsidis sucks juices from the flowering stalks. Seeds are eaten by birds such as the Ring-Necked Pheasant, Bobwhite, Wood Duck, Purple Finch, and Common Redpoll. The foliage is eaten by the cottontail rabbit.