How Is Blackjack Seed Suited To Its Method Of Dispersal
Bidens pilosaL.
- How Is Blackjack Seed Suited To Its Method Of Dispersal Method
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- How Is Blackjack Seed Suited To Its Method Of Dispersal Energy
- How Is Blackjack Seed Suited To Its Method Of Dispersal Methods
- Different Methods of Seed Dispersal in Plants. Dispersion of seeds is very crucial for propagation of plant species. While we see self-dispersal of seeds in some plants, others require external agents for the same. Read this Gardenerdy article to know how wind, water, animals, and gravity, disperse seeds.
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- How is the blackjack seed suited to its method of dispersal? 1.Do you think you can carry genes for traits you can’t physically see in yourself? For example, you may have brown eyes- can you carry genes for anot.
Bidens leucantha (L.) Willd.; Bidens sundaica (Blume)
Blackjack, Spanish needle, hairy beggar ticks, farmer's friend, cobbler's pegs, pitchforks, kichoma mguu (Kiswahili), labika (Acholi), muceege (Kikuyu), ononot (Lango)
Seed dispersal There is no animal alive that eats the avocado seed, and its too big to be transported by wind. It is believed to have evolved to be carried by a now extinct species. Dispersal is the process of organisms spreading from one place to another. All species, including plants, maintain or expand their range through dispersal. The Florida weave is a recommended trellising method that uses posts and twine. Stakes should be fitted about 5 feet apart with a tomato plant placed every 1.5 to 2 feet. A single tomato vine is attached to each stake using a soft cloth tie, starting 1 foot from the ground and every 12 inches thereafter as the plant trains up the pole.
How Is Blackjack Seed Suited To Its Method Of Dispersal Method
Asteraceae (Compositae)
Native to tropical America
Bidens pilosa is naturalised throughout the tropics.
Bidens pilosa is invasive in parts of Kenya, Tanzania and Uganda (Global Invasive Species Database).
Bidens pilosa can invade roadsides, crops, pastures, gardens, disturbed areas, fallow lands and urban open space
Bidens pilosa is an annualherb with an erecthabit to 1.5 m in height (Stanley and Ross 1983-1989). It is easily recognised by the elongated fruits that bear hooked bristles (burrs) that embed themselves in people's clothing as they brush past the stems.
Stems are square in cross section (quadrangular), mostly hairless and green to purplish in colour. The leaves are oppositely arranged with leaf stalks (petioles) 1-6.5 cm long. Their margins have forward pointing teeth (serrated). Leaf blades vary in shape. At the base of the plant, leaves tend to be simple and more or less oval in shape, higher up the plant leaves are mostly compound (pinnate) with 3-7 egg-shaped with broad end at base (ovate) leaflets, and the uppermost leaves are smaller and simple or with 3 leaflets (trifoliolate). Leaf or leaflet size varies from 1.5-7 x 0.5-3.5 cm.
Flower-heads are 7-8 mm across with yellow central (tubular) florets. Some plants have flower-heads with white or cream 'petals' (rayflorets) up to 1.5 cm long, however these 'petals' may be absent or quite small. Heads are arranged in branched inflorescences at the ends of the branches. Flowering occurs over most of the year. The seeds are black, flattened, linear in shape (0.4-1.6 cm long) with a row of two to four barbedawns (2-4 mm long) at one end.
Bidens pilosa normally behaves as an annualweed but at least one form, B. pilosa var. radiata, may behave as a perennial. One isolated plant can produce over 30,000 seeds, which are generally highly viable. Seeds germinate on the soil surface or in shallow soil (to a depth of 1 cm). Seeds at greater depths remain viable in the soil for many years. There is usually a great flush of germination after tillage of the soil. Seeds are widely dispersed through the fruits hook-like bristles that embed themselves in clothing and the fur of mammals and feathers of birds. They are also spread by wind, water and soil.
The fresh or dried tender shoots and young leaves are eaten in some cultures, especially in times of food scarcity. It is used as a medicinal plant in many regions of Africa.
Bidens pilosa is a serious weed in many cropping systems in many countries where it reduces yield because of its fast growth and competitive abilities which include allelopathic properties. One study found that B. pilosa is a serious weed in many cropping systems in many countries where it reduces yield because of its fast growth and competitive abilities which include allelopathic properties. One study found that B. pilosa competition reduced dry bean, Phaseolus vulgaris harvests by 48% in Uganda. Bidens pilosa is also a host and vector to harmful parasites such as root knot nematodes (Meloidogynespecies) and tomato spotted wilt virus (GISD 2010). It is also a weed of open areas where dense stands reduce access to roads, trails, and recreational areas, and can damage pavements and walls. Its burrs are a nuisance to people, as well as to sheep and goats. The burrs are also a seed contaminant.
B. pilosa has been included in the Global Invasive Species Database (GISD 2010).
The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.
The best form of invasive species management is prevention. As Bidens pilosa is so widespread this is unlikely to be possible in many instances.
If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.
Bidens pilosa can be controlled by persistent mowing, hoeing and hand pulling in order to prevent seed production. Thorough cultivation discourages growth. Chemical control regimes depend upon the cropping system in which one is working. Details for individual crops can be found in the CABI Invasive Species Compendium. When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.
Biological control agents against B. pilosa are yet to be developed.
Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.
CABI invasive species compendium online data sheet. Bidens pilosa (blackjack). CABI Publishing 2011. www.cabi.org/ISC. Accessed March 2011.
GISD (2010). Global Invasive Species Database online data sheet. Bidens pilosa (herb) www.issg.org/database. Accessed March 2011.
Kleinschmidt, H.E., Holland, A. and Simpson, P. (1996). Suburban Weeds. 3rd Edition. Department of primary Industries, Brisbane.
Stanley, T.E. and Ross, E.M. (1983-1989). Flora of South-eastern Queensland. Volume 2. Department of Primary Industries, Brisbane.
Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.
How Is Blackjack Seed Suited To Its Method Of Dispersal Using
This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).
BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke
The fruit has a single purpose: seed dispersal. Seeds contained within fruits need to be dispersed far from the mother plant, so they may find favorable and less competitive conditions in which to germinate and grow.
Some fruit have built-in mechanisms so they can disperse by themselves, whereas others require the help of agents like wind, water, and animals (Figure 1). Modifications in seed structure, composition, and size help in dispersal. Wind-dispersed fruit are lightweight and may have wing-like appendages that allow them to be carried by the wind. Some have a parachute-like structure to keep them afloat. Some fruits—for example, the dandelion—have hairy, weightless structures that are suited to dispersal by wind.
Figure 1. Fruits and seeds are dispersed by various means. (a) Dandelion seeds are dispersed by wind, the (b) coconut seed is dispersed by water, and the (c) acorn is dispersed by animals that cache and then forget it. (credit a: modification of work by “Rosendahl”/Flickr; credit b: modification of work by Shine Oa; credit c: modification of work by Paolo Neo)
Seeds dispersed by water are contained in light and buoyant fruit, giving them the ability to float. Coconuts are well known for their ability to float on water to reach land where they can germinate. Similarly, willow and silver birches produce lightweight fruit that can float on water.
Animals and birds eat fruits, and the seeds that are not digested are excreted in their droppings some distance away. Some animals, like squirrels, bury seed-containing fruits for later use; if the squirrel does not find its stash of fruit, and if conditions are favorable, the seeds germinate. Some fruits, like the cocklebur, have hooks or sticky structures that stick to an animal’s coat and are then transported to another place. Humans also play a big role in dispersing seeds when they carry fruits to new places and throw away the inedible part that contains the seeds.
How Is Blackjack Seed Suited To Its Method Of Dispersal Energy
All of the above mechanisms allow for seeds to be dispersed through space, much like an animal’s offspring can move to a new location. Seed dormancy, which was described earlier, allows plants to disperse their progeny through time: something animals cannot do. Dormant seeds can wait months, years, or even decades for the proper conditions for germination and propagation of the species.