Kali is a genus of annual or short-lived plants in the subfamily Salsoloideae of the family Amaranthaceae, placed within the order Caryophyllales. The genus is closely allied to Salsola and has had a contested taxonomic history: originally segregated from Salsola, it was recognized as comprising approximately 23 species before being subsumed back into Salsola following a nomenclatural conservation proposal by Mosyakin et al. (2014) that was approved by the General Committee of the XIX International Botanical Congress.
Members of Kali are characterised by their adaptation to arid and disturbed habitats and their distinctive wind-dispersal strategy: at maturity the plant breaks off at the base and tumbles across open ground driven by the wind, scattering seeds as it rolls. This habit gives rise to the well-known common name tumbleweed, as well as rolypoly and buckbush. Species of Eurasian origin, particularly the widespread Kali tragus (Russian thistle), have become significant cosmopolitan weeds following introduction to North America and Australia.
The type species of the genus is Kali turgidum (synonym Salsola kali L.), and the species Kali tragus (synonym Salsola tragus, authorship Scop.) is arguably the most ecologically prominent member — the iconic tumbleweed of western North American landscapes. The approximately 23 species are distributed across Europe, Asia, North Africa, and regions where members have become naturalised as introduced weeds.
Taxonomy Notes
Kali was segregated from the large genus Salsola within subfamily Salsoloideae (Amaranthaceae). In 2014, Mosyakin et al. proposed conserving Salsola kali (= Kali turgidum) as the nomenclatural type for Salsola; the General Committee of the XIX International Botanical Congress approved this proposal, with the result that species formerly placed in Kali are now treated under Salsola, while species related to Salsola soda were transferred to a separate genus.
Distribution
Members of Kali are native primarily to Europe, central and western Asia, and North Africa, typically colonising dry, disturbed, and saline soils. Several species, most notably Kali tragus (Russian thistle), have been introduced as weeds to North America, Australia, and other regions, where they are widespread in arid and semi-arid landscapes.
Ecology
Species of Kali are classic pioneers of open, disturbed, and saline habitats — roadsides, field margins, steppes, and desert edges. Their defining ecological trait is the tumbleweed growth form: the entire above-ground plant detaches at the root collar after fruiting and is dispersed by wind across open ground, releasing seeds along the way. This strategy enables rapid colonisation of bare ground over large distances and contributes to the invasive success of introduced species such as Kali tragus in North American grasslands and rangelands.
