Fossils dating from before the Pleistocene glaciations show that species of Laurus were formerly distributed more widely around the Mediterranean and North Africa, when the climate was more humid and mild than at present. It is currently thought that the drying of the Mediterranean basin during the glaciations caused Laurus to retreat to the mildest climate refuges, including southern Spain, Portugal and the Macaronesian islands. With the end of the last glacial period, L. nobilis recovered some of its former range around the Mediterranean.
The number of species in the genus has not yet been fully resolved. The following may or may not be included.
The bay laurel, with the botanical name Laurus nobilis, of the plant family Lauraceae), is also known as sweet bay, bay tree (esp. United Kingdom), true laurel, Grecian laurel, laurel tree, or simply laurel.
It is an aromatic evergreen tree or large shrub with green, glossy leaves, native to the Mediterranean region. It is one of the plants used for bay leaf seasoning in cooking. Under the simpler name "laurel," Laurus nobilis figures prominently in classical Greek, Roman, and Biblical culture.
Worldwide, many other kinds of plants in diverse families are also called "bay" or "laurel," generally due to similarity of foliage or aroma to Laurus nobilis, and the full name is used for the California bay laurel (Umbellularia), also in the family Lauraceae.