We examine various aspects of Joseph Quer's Flora española (1762–1764, 1784), taking into consideration the contributions made by Casimiro Gómez Ortega and proposing that he be credited as a co-author on the last two volumes of the work. Flora española comprises 2602 species, 2493 of which are vascular plants, including both wild and cultivated species. When assigned to the currently accepted species of Flora iberica, we obtain 1690 native or naturalized plant species (28 % of the total Spanish species). Most of the reported species correspond to common plants, only 3 % are considered narrowly distributed species and no more than 5 % are endemic species. In Flora española only two species are proposed as new. The limited number of new taxa may be due to Quer's self-taught background, strongly influenced by Tournefort's work, and the unfavourable scientific environment, characterized by the lack of resources and supporting institutions. By far the weakest points of Flora española are the names listed in alphabetical order and the use of old polynomials instead of Linnaean binomials. In contrast, the study of dried plants then kept at herbaria constituted a suitable working methodology, which made this Flora a solid base for subsequent works in the Iberian Peninsula. We also address the extensive field work carried out by Quer: he visited 632 different localities spread over most of the Iberian Peninsula. The information provided in Flora española, together with a thorough review of Quer's herbarium vouchers, the labels of which do not include information on localities, allows us to gain valuable insights into some rare and potentially extinct species.