Bidens subalternans is a species of flowering plant in the family Asteraceae, commonly known as Bidens subalternans. This herbaceous annual is recognized for its distinctive floral structure and its role within its native ecosystems. As a member of the Bidens genus, it shares characteristics with other "beggarticks" or "burmarigolds," a group of plants often found in disturbed habitats and known for their achenes that readily attach to passing animals or clothing. Physically, Bidens subalternans typically presents as an erect or spreading annual herb, reaching heights that can vary but often fall within the range of 30 to 100 centimeters. Its stems are generally smooth or sparsely pubescent. The leaves are arranged oppositely along the stem and are typically pinnately compound, with leaflets that are lanceolate to ovate in shape and possess serrated margins. The inflorescence is a capitulum, or flower head, characteristic of the Asteraceae family. These flower heads are usually borne singly at the tips of stems or branches. The ray florets, when present, are typically white or pale yellow, though their presence and prominence can vary. The disc florets are usually yellow and form the central part of the flower head. Following pollination, the plant produces achenes, which are the characteristic fruits of Bidens species. These achenes are typically flattened and possess two or more awnings or "bristles" that are barbed, facilitating their dispersal. The native distribution of Bidens subalternans is primarily within South America, with documented occurrences in countries such as Brazil and Argentina. It thrives in a variety of natural habitats, often colonizing open, disturbed areas. These can include roadsides, fallow fields, pastures, and the edges of forests. In terms of cultivation, Bidens subalternans is not widely cultivated as an ornamental plant, likely due to its weedy tendencies in some regions and its less showy appearance compared to other ornamental Bidens species. However, where it occurs naturally, it plays a role in the local flora. While Bidens subalternans is not extensively documented for specific ornamental, medicinal, or culinary uses, its ecological significance is noteworthy. As a pioneer species in disturbed environments, it can contribute to soil stabilization and provide a food source for certain insects. The achenes' barbed awnings are a remarkable adaptation for seed dispersal, demonstrating a classic example of epizoochory, where seeds are carried externally by animals. This mechanism ensures the plant's propagation across its habitat. Further research may uncover more specific biological or ecological roles for this particular Bidens species.