Taraxacum kok-saghyz
Taraxacum kok-saghyz, often abbreviated as TKS and commonly referred to as the Kazakh dandelion, rubber root, or Russian dandelion, is a species of dandelion native to Kazakhstan, Kirghizia and Uzbekistan, that is notable for its production of high quality rubber. "T. kok-saghyz" was discovered in Kazakhstan in 1932 by scientists serving the Soviet Union in an effort to find a domestic source of rubber. Etymology. "Kok-saghyz" is derived from the Kazakh "kök-sağız" (көк-сағыз), with "kök" meaning root and "saghyz" meaning rubber or gum. Its latex was traditionally used as a kind of  chewing gum. Description. "Taraxacum kok-saghyz" is a perennial plant with a yellow composite flower characteristic of the genus "Taraxacum". Each flower head may be approximately one inch in diameter and be made up for 50 to 90 florets. Plants may contain 25 to 50 leaves arranged in one or more rosettes at the upper end of the root. "Taraxacum kok-saghyz" can be differentiated from the common dandelion ("Taraxacum officinale") by its generally smaller, grayish green leaves and hornlike structures on the bracts surrounding the bud. Flowers are hermaphrodite, insect-pollinated (entomophilous) and are on stalks that reach about  a foot in height. "Taraxacum kok-saghyz" is usually in flower from May through June, with seeds ripening from June through July. It is a diploid species that reproduces sexually, and produces good pollen. Another species, a triploid apomict that also has horned bracts and produces rubber, "T. brevicorniculatum" Korol. has frequently been misidentified as "T. kok-saghyz". Growing conditions. "Taraxacum kok-saghyz" does best in loose, well-drained soils with high moisture retention and a pH between 5.5 and 8.5, in full or nearly-full sun. Utility. Rubber. The Soviet Union cultivated "Taraxacum kok-saghyz," together with Taraxacum hybernum  and Scorzonera tau-saghyz, on a large scale between 1931 and 1950—notably during World War II—as an emergency source of rubber when supplies of rubber from "Hevea brasiliensis" in Southeast Asia were threatened. The United States, the UK, Germany, Sweden and Spain also cultivated the plant for the same reason. During this time period, the highest yields achieved by the U.S. reached 110 kg of rubber per hectare, while the USSR achieved yields of 200 kg of rubber per hectare. With the conclusion of World War II and the return of affordable "Hevea brasiliensis" rubber (which has 8  to 10 times the yield), the majority of "T. kok-saghyz" programs ceased. The Raisko sub-camp of Auschwitz was a production factory for the plant. Some of the women who been deported on the Convoi des 31000 worked on its production there. Attention on "T. kok-saghyz" has revived due to allergic reactions to "Hevea" rubber used in medical devices, and to shortcomings in the supply of rubber from "Hevea brasiliensis". One threat to "Hevea brasiliensis" rubber production is the South American Leaf Blight (SALB), which has afflicted conventional rubber production in South America since 1934. This blight may  spread to the "Hevea brasiliensis" trees in Southeast Asia, which are genetically very similar to each other and to those of South America. Furthermore, land used for rubber production is being converted to palm-oil plantations in order to produce biofuel, and labor costs reduce the profitability of "Hevea brasiliensis" plantations, as each tree must be manually tapped in order to harvest its latex. Rising oil-prices limit the economic viability of synthetic rubbers, and synthetic equivalents often cannot pragmatically replace natural rubber. In May 2019 German tire-maker Continental AG announced it was about to begin production of  the "first bicycle tyre made with sustainable rubber from dandelions", which it intended to grow on the grounds of its own manufacturing plants, avoiding several of the traditional issues with "H. brasiliensis" latex—from the long lead-time between planting and cultivating (only six months for the dandelion, rather than seven years for the rubber tree) and volatile prices of the product due to the long transport-distances between places where the rubber can be grown and the company's factories. Researchers have started to develop "Taraxacum kok-saghyz" cultivars which are easier to cultivate and which produce more and  better rubber as part of a large research project at many institutions. Dandelion by-products. Inulin produced by "T. kok-saghyz" is a sugar that could be used in non-food applications or be turned into bioethanol through fermentation. The remaining plant biomass could be used to produce biogas.