This study contributes to the knowledge of the mythical-descriptive conception of the vegetable kingdom in Homeric times, based on the botanic and ethnobotanic references made in the texts of the Iliad and the Odyssey. The aim of the work is to examine the biodiversity, ecology, and uses of indigenous and cultivated plants; the aesthetic dimension and the sense of the botanical simile; and the keys that the poem offers to dwell into the mythical geography underlying the vision of nature that permeates the period. The examination was done on the basis of the elaboration of a Catalog with the Greek names of plants registered in Homer, their Latin transliterations, the places where they appear, the Spanish and scientific names of the taxa and the mentioned classes of relationhips. The evaluation of the relative importance and relationships of the 59 Greek plant names cited in the Catalog demonstrate that: (i) In the description of indigenous and cultivated plants, native forest communities and their component tree species attain greater importance (19%), including oaks, olive trees, ashes and several conifer species. In the cultural landscape, cereals and grapevines predominate. (ii) Among the botanical references made by Homer, the poetic form of simile -emphasizing comparisons with vegetable elements- is second in importance (17%). (iii) The mythical elements represent 13% of the references, which are given magic-therapeutic powers or assigned supernatural characters focused on certain plants and plant communities, as sacred plants in ritual ceremonies. (iv) The remaining botanical classes make reference to practical uses of the flora, as objects for construction, arts and crafts, sources of foods, forage and so on. We highlight two main conclusions: (i) the founding role of the Homeric poems in regard to Natural History, by introducing both nomenclatural and terminological botany, (ii) the transcendence of the poetic comparison and Homeric myth that considers plants as symbols of the sense and human condition.