Peaches and nectarines are both fruits of the species Prunus persica. Nectarines are varieties with a smooth skin that are usually also smaller, firmer, and more aromatic than their fuzzy siblings. The words “peach” and “persica” come from “Persia,” by way of which the fruit reached the Mediterranean world from China by about 300 BCE.
Modern peach and nectarine varieties fall into a handful of categories. Their flesh may be white or yellow, and either firm or melting, strongly attached to the large central stone (clingstone) or easily detached (freestone). The genetically dominant characteristics are white, melting, freestone flesh. Yellow varieties were developed mainly after 1850, and firm clingstone varieties have been bred mainly for drying, canning, and improved tolerance of shipping and handling. The yellow coloration comes from a handful of carotenoid pigments, beta-carotene among them; rarer red varieties contain anthocyanins (as the skin often does). Peaches begin to ripen at the stem end and along the groove, or “suture,” and are said to continue their flavor development even after harvest. The distinctively aromatic flavor of peaches and nectarines comes largely from compounds called lactones, which are also responsible for the aroma of coconut; some varieties also contain clove-like eugenol.