Latexes may be natural or synthetic. Latex as found in nature is a milky fluid found in 10% of all flowering plants It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins, and gums that coagulates on exposure to air. Since the 17th century, latex has been used as a term for the fluid substance in plants. It serves mainly as defense against herbivorous insects. Many people are allergic to latex. Natural rubber is the most important product obtained from latex; more than 12,000 plant species yield latex containing rubber, though in the vast majority of those species the rubber is not suitable for commercial use. This latex is used to make many other products as well, including mattresses, gloves, swim caps, condoms, catheters and balloons, as well as being a component of some yoga mats! The word is also used to refer to natural latex rubber; particularly for non-vulcanized rubber. Such is the case in products like latex gloves and latex clothing.