Oils and fats, the principal plant lipids, are esters of long-chain fatty acids and alcohol or of closely related derivatives. Chemically fixed oils and fats are composed predominantly of triacyl glycerols having identical or different fatty acids esterified to the three hydroxyl positions on the glycerol molecule. Numerous fatty acids are now known in plants, common ones being saturated or simple unsaturated compounds of C16- C18 –chain length. Palmitic acid (C16 acid), is the major saturated acid in leaf lipids and it also occurs in quantity in seed oils such as groundnut oil. Stearic acid (C18) is less prominent in leaf lipids, but is a major saturated acid in seed fats in a number of plant families. Unsaturated acids are widespread in both leaf and seed oils. Oleic acid comprises 80% of the fatty acid content of olive oil, 59% in groundnut oil and is often accompanied by the di-unsaturated linoleic acid. The tri-unsaturated linoleic acid is common, occurring in linseed oil along with linoleic and oleic acids. Rarer fatty acids such as petroselinic acid, erucic acid, and sterculic acids are found as lipid components occurring characteristically in seed oils of a few related plants.

Waxes are esters of high molecular weight fatty acids and monohydric alcohols and the chain length varies from 24–36 carbon atoms. They vary with nature of the monohydric alcohol which could be a sterol such as cholesterol, stigmasterol, ergosterol, or others such as acetyl alcohol, myricyl alcohol, etc. In addition, many plant waxes contain varying quantities of higher saturated hydrocarbons, long-chain ketones, and secondary alcohols. Higher fatty esters of carotenols, free and combined sterols in combination with higher acids are also found. A number of glycerol containing fatty substances with physical properties similar to that of waxes are also referred to as true waxes. Japan wax is one such wax and it has a high melting point and is non-greasy to touch because of the presence of high molecular weight dibasic acids.

In addition to triacylglycerols, mono and di-acylglycerols and free fatty acids may be present in oils and fats depending on the maturity and physical condition of the natural source at the time of lipid extraction.

Phospholipids are characterized by a phosphate ester joined to either choline, ethanolamine, inositol, or serine attached to the C-1 position of glycerol and fatty acids are esterified to the C-2 and C-3 positions. Diacylgalactoglycerol and diacylgalabiosylglycerol are glycolipids playing an important role in chloroplast metabolism.

Leaf cutin acids, though not fat components, are formed from fatty acids by chain elongation and they have a longer chain length ranging from C24-C32. These acids have hydroxyl groups in their structures.