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Bidens alba


Bidens alba, which belongs to the family Asteraceae, is most commonly known as shepherd's needles, beggarticks, Spanish needles or butterfly needles.<ref name="FLORIDATA">Bidens alba. Ed. Linda C. Duever. FLORIDATA: 21 Nov. 2003. 27 May 2013.</ref> Bidens means two- toothed, describing the two projections found at the top of the seeds, and alba refers to the white ray florets.<ref name="Futch">Futch, Stephen H., and David W. Hall2. "Identification of Broadleaf Weeds in Citrus1". Gainesville: Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Science, University of Florida, 2002. N. 27 May 2013.</ref> This plant is found in tropical and subtropical regions of North America, Asia, South America, and Africa,<ref name="Lady Bird">"Bidens alba." University of Texas At Austin. Lady Bird Johnson Wildflower Center, n.d. Native Plant. 28 May 2013.</ref> situated in gardens, road sides, farm fields and disturbed sites.<ref name="Deane">Deane, Green. "Spanish Needles, Pitchfork Weed". Eat the Weeds and other things too, 19 Oct.2011.</ref> B. alba is an annual or short-lived perennial, which is considered an weed in the United States.<ref name="Futch"/> However, B. alba leaves are edible and can be used as medicinal remedies.<ref name="FLORIDATA"/>


Bidens alba is a vascular plant. It has a similar root and stem system to others in the dicot family Asteraceae.<ref name="Hall">David W. Hall, Vernon V. Vandiver, and Jason A. Ferrell2. "Common Beggar's-tick (Hairy Beggar's-tick), Bidens alba (L.)" DC.1. University of Florida IFAS Extension, SP37 (1991):N. Web. 25 May 2013.</ref> After germinating, the roots progress into a tap root that grows vertically in the ground.<ref name="FLORIDATA"/> The primary tissue of the apical meristems increases the length of the plant and the secondary roots of the lateral meristems give rise to the width. B. alba grows to a height of approximately five feet tall.<ref name="Futch"/>

The stem of B. alba plant emerges from the taproot, yet the bent stem at the base also has the ability to grow into roots at the lower nodes. Stems are mostly hairless and green to purplish in color.<ref name="Deane"/> The vascular bundle provides nutrients throughout the plant, with the phloem transporting water from the roots and the xylem obtaining food from the leaves.<ref name="Futch"/>

Bidens alba leaves, which are simple on the opposite side and compound on the underneath, are Template:Convert long and Template:Convert wide.<ref name="Lady Bird"/> The underside leaf is hairy, and has toothed edges.<ref name="Deane"/> The leaves may be lobed, depending on the species. Some have teeth and some do not; each node produces two leaves along the stem.<ref name="Lady Bird"/>

Each flowering head of B. alba, which is small, appears in radial symmetry.<ref name="FLORIDATA"/> The flowers on this plant are depicted as daisy-like due to the larger white petals and the very small yellow flowers which are located at the end of the branches.<ref name="Hall"/> Colors of the flower-heads of Bidens alba vary depending on the subspecies; some B. alba have yellow, tubular central blossoms and others may have flower-heads with white or cream petals (Template:Convert long); eventually they form black linear seeds, yielding approximately 1200 seeds per plant.<ref name="Futch"/>


Bidens alba is a fast-growing, fast-spreading weed due to its enormous number of seeds and the ability to re-grow from stems.<ref name="Lady Bird"/> In sub-tropical to tropical conditions, B. alba can grow almost everywhere in full sun with little or no moisture. The most growth occurs in organic matter with loose soil;<ref name="FLORIDATA"/> however, they can also propagate well on sand and lime-rocks in non-irrigated habitats. The seeds are dispersed mainly by animals or humans, although some are also carried by wind and water.<ref name="Deane"/>


Bidens alba provide a nectar source for butterflies and honey-bees. People in South Africa, Zulus and Indians consume the fresh or dried leaves by boiling them.<ref name="Lady Bird"/> Young leaves of B. alba may also be eaten as a salad.<ref name="Deane"/>