Lachenalia reflexa
Encyclopedia
Lachenalia reflexa, commonly known as Yellow Soldier, is species
of the genus
Lachenalia
native to South Africa
.
, the species is an introduced weed
. The Yellow Soldier species is so dangerous to natural flora
and fauna
that it has been placed on the national weed alert program, one of only 28 weeds to be recognised as extremely dangerous to natural bushland.
The first of these two methods is simply dropping the seeds of the plant up to 20 cm (8") away from the base of the original plant. Given that each flower produces between 40 and 60 seeds, and that each plant can produce up to ten flowers, the ability to spread is incredible. Yellow Soldier can grow in densities of up to 400 plants per square metre, with each plant capable of reaching full reproductive potential. This density prevents native plants from reclaiming lost ground.
The second method of seed dispersal is by clinging to the feet of native animals and humans. The small, black seeds become stuck in between the toes of animals and humans or in the tread of shoes. When the seed is eventually jolted out of its position, it falls to the ground and begins to germinate. Within two years it will have reproduced enough times to reach optimal density in a square metre, and gains another square metre or two every year from then on, with a possibly exponential growth
rate.
Yellow Soldier damages not only native flora, but fauna as well. Its ability to completely dominate an area prevents native herbs and grasses from growing. In turn, this eliminates food sources for native fauna, lowering fauna levels to the point of non-existence.
Controlled burning is also ineffective; it actually increases the number of Yellow Soldiers in the area. In studies conducted, it has been found that fire increases the germination rate of Yellow Soldier seeds, and does not kill off any of the plants, due to its ability to grow back from its root system. The Yellow Soldier also germinates faster after a fire than native plants, allowing it complete dominance over a larger area than before the fire.
The only effective way to remove Yellow Soldier is through spot-spraying of herbicide
s. Once again, however, the ability to quickly germinate from seed means that multiple courses of spraying must be done in order to completely eliminate Yellow Soldier, and allow native species the chance to reclaim the soil. The herbicide used has been specially developed to kill only Yellow Soldier, but is very expensive, and can usually only be done through government funding. This prevents most environment and bush care groups from eliminating the species, and thus allowing it the chance to spread further.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Lachenalia
Lachenalia
Lachenalia is a genus of bulbs in the family Asparagaceae, subfamily Scilloideae, which are usually found in Namibia and South Africa. Most of these plants have a dormancy period, and the new roots of these plants will always grow every year. Lachenalia is named after the Swiss botanist Werner de...
native to South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
.
South Africa
The species is a native to South Africa, particularly in Cape Province. The plant flourishes where there is a winter rainfall and becomes dormant during dry seasons.Australian weed
In AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, the species is an introduced weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
. The Yellow Soldier species is so dangerous to natural flora
Flora
Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...
and fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
that it has been placed on the national weed alert program, one of only 28 weeds to be recognised as extremely dangerous to natural bushland.
Seed dispersal
Reaching approximately 10 cm (4") when in flower, this weed spreads through two main methods, both of which lend to its common name.The first of these two methods is simply dropping the seeds of the plant up to 20 cm (8") away from the base of the original plant. Given that each flower produces between 40 and 60 seeds, and that each plant can produce up to ten flowers, the ability to spread is incredible. Yellow Soldier can grow in densities of up to 400 plants per square metre, with each plant capable of reaching full reproductive potential. This density prevents native plants from reclaiming lost ground.
The second method of seed dispersal is by clinging to the feet of native animals and humans. The small, black seeds become stuck in between the toes of animals and humans or in the tread of shoes. When the seed is eventually jolted out of its position, it falls to the ground and begins to germinate. Within two years it will have reproduced enough times to reach optimal density in a square metre, and gains another square metre or two every year from then on, with a possibly exponential growth
Exponential growth
Exponential growth occurs when the growth rate of a mathematical function is proportional to the function's current value...
rate.
Danger as an introduced weed
Yellow soldier is presenting a problem in Australia where it is considered a pernicious introduced weed.Yellow Soldier damages not only native flora, but fauna as well. Its ability to completely dominate an area prevents native herbs and grasses from growing. In turn, this eliminates food sources for native fauna, lowering fauna levels to the point of non-existence.
Control Methods
The reason this weed is so hard to control is its ability to reproduce in such great numbers, and the damage it does when removed. Seeds of the Yellow Soldier are next to impossible to see in the soil or on the shoes of removalists, and germinate easily, negating the effect of the removal program. Removal by hand is labour intensive, with only 4m² (42 square feet) being removed in a 6-hour period (Weed Management Guide). The ability to grow back from its root system means that the entire plant must be removed from the ground, allowing other weeds to germinate.Controlled burning is also ineffective; it actually increases the number of Yellow Soldiers in the area. In studies conducted, it has been found that fire increases the germination rate of Yellow Soldier seeds, and does not kill off any of the plants, due to its ability to grow back from its root system. The Yellow Soldier also germinates faster after a fire than native plants, allowing it complete dominance over a larger area than before the fire.
The only effective way to remove Yellow Soldier is through spot-spraying of herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
s. Once again, however, the ability to quickly germinate from seed means that multiple courses of spraying must be done in order to completely eliminate Yellow Soldier, and allow native species the chance to reclaim the soil. The herbicide used has been specially developed to kill only Yellow Soldier, but is very expensive, and can usually only be done through government funding. This prevents most environment and bush care groups from eliminating the species, and thus allowing it the chance to spread further.