Alkanes are the most basic group of hydrocarbons that have a single bond. These saturated hydrocarbons are predominant in plants. The simplest alkane is methane, which forms the major component of natural gas you use for fuel. Methane is mined from the earth or from decaying swamps. Naturally, when plants and animals decay in the absence of oxygen, methane forms. Toluene, found in propane, can dissolve substances you cannot dissolve in water, such as the binder in some paint. Methyl-branched alkanes are also found in insect species. Alkanes are found in needle wax of the Pinaceae picea omorika. They are also found at the outer surface of insects and several marine organisms.
Alkenes are unsaturated hydrocarbons that contain single or double bonds. The simplest alkenes are ethene, butene and propene. Ethylene is used to make plastic bags as well as asphalt, essential in the making of roads. Ripened fruits also produce ethylene. Fruits picked before they ripen can also be ripened artificially when exposed to ethylene. Alkenes also include the hydrocarbons you find at the external surface of plant leaves. Most microalgae have alkene n-C21:6. A few species also have the n-C21:5 alkene. Several microalgae contain long-chain unsaturated alkenes from 19 to 38 carbon atoms and one to four double bonds.
Wachen Roder discovered this hydrocarbon in 1831 after he crystallized carrot roots. Caroteneids occur as pigments in algae, bacteria and higher plants. They are used to derive lycopene --- found in tomatoes, carrots and flowers --- which plays a role in controlling prostate cancer. In fact, eating tomatoes may lower the risk of prostate cancer. These hydrocarbons are also essential components that enhance photosynthesis by plants. When you consume carotenoids, your cell-mediated immune responses become enhanced.
Cyclic hydrocarbons can be classified into monocyclic and polycyclic species. Monocyclic hydrocarbons comprise several branched-alkylbenzenes found in hydrocarbon you get in the brown algaes ectocarpus, adenocystis and sphacelaria. They play the role of pheromone in marine brown algae as well, enhancing the sweet aroma of a ripening mango. Naphthalene, found in magnolia flowers, protects plant tissues against destructive insects. It may also attract insects to pollinate the plant. Biosynthetic studies suggest unsaturated fatty acids as a sign of these hydrocarbons. Polycyclic hydrocarbons are traceable in plants and contain fused rings that have carbon or heterocycles, as well as foreign atoms such as oxygen or nitrogen.