''Bidens alba'', which belongs to the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae ...

, is most commonly known as shepherd's needles, beggarticks, Spanish needles, or butterfly needles.''Bidens alba''. Ed. Linda C. Duever. FLORIDATA: 21 Nov. 2003. 27 May 2013. ''Bidens'' means two- toothed, describing the two projections found at the top of the seeds, and ''alba'' refers to the white ray florets.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. This plant is found in tropical and subtropical regions of North America, Asia, South America, and Africa,"Bidens alba." University of Texas At Austin. Lady Bird Johnson Wildflower Center, n.d. Native Plant. 28 May 2013. situated in gardens, road sides, farm fields and disturbed sites.Deane, Green. "Spanish Needles, Pitchfork Weed". Eat the Weeds and other things too, 19 Oct.2011. ''B. alba'' is an annual or short-lived

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

, which is considered a

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

in the United States. However, ''B. alba'' leaves are edible and can be used as medicinal remedies.

Description

''Bidens alba'' is a

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...

. It has a similar root and stem system to others in the

dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, t ...

family ''Asteraceae''.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. After germinating, the roots progress into a tap root that grows vertically in the ground. The primary tissue of the

apical meristems The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells conti ...

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. 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. The

vascular bundle A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in the stem, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition will inclu ...

provides nutrients throughout the plant, with the

xylem Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived fr ...

transporting water from the roots and the

phloem Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is ...

obtaining food from the leaves. ''Bidens alba'' leaves, which are simple on the opposite side and compound on the underneath, are long and wide. The underside leaf is hairy, and has toothed edges. The leaves may be lobed, depending on the species. Some have teeth and some do not; each node produces two leaves along the stem. Each flowering head of ''B. alba'', which is small, appears in

radial symmetry Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...

. The flowers on this plant are depicted as daisy-like due to the larger white

petals Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usuall ...

and the very small yellow flowers which are located at the end of the branches. 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 ( long); eventually they form black linear seeds, yielding approximately 1200 seeds per plant.

Cultivation

''Bidens alba'' is a fast-growing, fast-spreading weed due to its enormous number of seeds and the ability to re-grow from stems. In

sub-tropical The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north an ...

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; however, they can also propagate well on sand and lime-rocks in non-irrigated habitats. The seeds are dispersed mainly by

animals Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

, although some are also carried by wind and water.

Uses

''Bidens alba'' provide a nectar source for

butterflies Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises t ...

and honey-bees. Bidens is a nutrient dense wild plant, boasting a similar nutrient profile to

kale Kale (), or leaf cabbage, belongs to a group of cabbage (''Brassica oleracea'') cultivars grown for their edible leaves, although some are used as ornamentals. Kale plants have green or purple leaves, and the central leaves do not form a head ...

- high in fiber and proteins, carotenes, folate, and magnesium. People in

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...

, Zulus, and Indians consume the fresh or dried leaves by boiling them. Young leaves of ''B. alba'' may also be eaten as a salad. ''Bidens alba'' contains saponins, so older leaves may be unpleasant to the taste and may upset the stomach. The dried leaves of the B. Alba also make a good tobacco substitute.

References

{{Taxonbar, from=Q2901708

alba ''Alba'' ( , ) is the Scottish Gaelic name for Scotland. It is also, in English language historiography, used to refer to the polity of Picts and Scots united in the ninth century as the Kingdom of Alba, until it developed into the Kingdom ...

Plants described in 1753 Taxa named by Carl Linnaeus