Lachenalia reflexa, commonly known as yellow soldier, is species of the genus Lachenalia native to South Africa.
The species is a native to South Africa, particularly in the Cape Province. The plant flourishes where there is winter rainfall and becomes dormant during dry seasons.
In Australia, 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.
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, propagation may be rapid. 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 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.
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 herbicides. 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 developed to kill only yellow soldier is expensive and therefore 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.