Bidens Pilosa Fruit

Mature seed head with barbed awns.

Bidens pilosa fruit. Pappus awns 2 4 2 4 mm yellow. Kissmann and groth 1993 distinguish bidens subalternans on the basis that it has four awns on the achene but other authors treat this as synonymous with b. Bidens alba also known as beggar ticks is closely related to b. Alba as a florida native and b.

Pilosa as separate species and classify b. Seedling of cobbler s pegs. Germination of the short achenes was found to be enhanced by red light treatment scarification applied hormones leaching and increased oxygen tensions. A flowerhead with fruit forming.

The long achenes were found to germinate readily under a wide range of conditions while the short achenes showed fairly exacting germination requirements. Seed maturing barbed awns visible. Capitula with 5 8 ray flowers with well developed rays 5 16 mm long and involucral bracts numbering mostly 12 vs. Bidens pilosa is an annual plant producing an erect much branched stem up to 100cm tall though the plant can often flower seed and then die when much smaller.

Pilosa and some authors do not differentiate between the two grouping both species as b. Pilosa with capitula without ray flowers or with short rays up to 3 mm and involucral bracts numbering 7 10. 4 16 mm narrowly cylindric or slightly compressed 4 angled black short rough hairy. The atlas of florida plants and the usda natural resources conservation service recognize both b.

Light sandy medium loamy and heavy clay soils. Acid neutral and basic alkaline soils. It is in flower from may to october. Dimorphic fruits of bidens pilosa were tested separately for differences in germinability and seedling development.

It cannot grow in the shade. Bidens is the scientific name for a genus comprised of close to 200 species of herbaceous plants in the aster family. Bidens pilosa is a annual growing to 1 m 3ft 3in. Pilosa as an introduced species.

Bidens pilosa can be recognized by the elongated bur like fruits that bear recurved or hooked bristles which have played an important role in its spread holm et al 1977. The species is hermaphrodite has both male and female organs and is pollinated by bees hover flies. Bidens pilosa is an annual species of herbaceous flowering plant in the daisy family asteraceae its many common names include black jack beggarticks farmer s friends and spanish needle but most commonly referred to as cobblers pegs it is native to the americas but is widely distributed as an introduced species in other regions worldwide including eurasia africa australia south america.