Latex of some plants containing long chain hydrocarbons is considered to be a good substitute for liquid fuels or petroleum. Such plants having large amount of latex with long chain hydrocarbons are called petroplants. Cultivation of petroplants is also a part of energy-cropping. The most common petroplants belong to families of euphorbiaceae, asclepiadaceae, apocynaceae, compositae, labiatae, sapotaceae, urticaceae, etc., which have property of converting large amounts of their photosynthates into latex with hydrocarbons. The use of these petroplants may reduce the pressure on liquid fuel or petroleum.