Chorological and morphological data concerning species of the genus "Ambrosia" L. ("Compositae") present on the Iberian Peninsula.

Abstract

A chorological study of the species of the genus Ambrosia L. (Compositae) present on the Iberian Peninsula has been performed. The species were Ambrosia maritima L., A. tomentosa Nutt., A. trifida L., A. artemisiifolia L., A. psilostachya DC. and A. tenuifolia Spreng. Additionally, using material from the herbarium and samples collected by the authors, we carried out a morphological and micromorphological study of the leaves and fruits of the species examined, in the latter case using a scanning electron microscope. The data obtained allowed the elaboration of two keys for the determination of these species; one based on leaf characteristics and the other on floral and carpological aspects. The corological study revealed that the penetration of the neophyte plants occurs through the Mediterranean and Atlantic littoral areas, first colonizing habitats altered by human activity, such as roadsides, railway lines, maritime dunes, abandoned crop lands and the banks of rivers and streams.