Prickly Russian thistle

Description

Kali tragus is a species of flowering plant in the family Amaranthaceae. It is known by various common names such as prickly Russian thistle, windwitch, or common saltwort. It is widely known simply as tumbleweed because in many regions of the United States, it is the most common and most conspicuous plant species that produces tumbleweeds. Informally, it also is known as "'salsola", which was its generic name until 2007. For a brief phase during its youth, it may be grazed but afterwards becomes too spiny and woody to be edible to most wildlife and livestock (if it is not processed first). Mature specimens are often more than a meter in diameter. As its fruits mature, the diaspore of the plant dies, dries, hardens, and detach from its root. This detached anatomical part of Kali tragus is called a tumbleweed, which is why Kali tragus is colloquially called "tumbleweed" (although there are many other plant species that also produce tumbleweeds). Once mature, dry, and detached from the plant, this tumbleweed will tumble (i.e. roll) due to the force of the wind. As this dead structure tumbles in the wind, it gradually degrades and falls apart, thereby spreading (possibly as many as 200,000) seeds. If it happens to come to rest in a wet area then it can germinate rapidly, even with very small amounts of moisture. It has a high tolerance of salinity and can successfully compete with many native plants in certain environments, such as along sea beaches and especially in grassland, desert, or semiarid regions. Consequently, it now occupies a wide variety of habitats. Native to Eurasia, Kali tragus has proven to be highly invasive as an introduced species and rapidly became a common ruderal weed of disturbed habitats throughout the world. The tumbleweed's tumbling is known to damage non-native plants and environments and its highly flammable nature also sometimes helps wildfires spread, especially during windy conditions. An ignited tumbleweed may spread a fire across firebreaks and may even ignite buildings or structures that it stops against.