A floristic-taxonomic survey of Raphanus L. and Alyssum L. (Cruciferae) in Israel

Crucifers are one of the species-richest and widespread plant families in Israel and in the Mediterranean Basin. Yet, crucifers remained for many years the least studied of Israel large families. This diversity in forms and distributions created great confusion in the circumscription of taxa, so that the position of many described taxa remains unclear.

In this project we aim to focus on two genera, each representing a different difficulty. Raphanus (radish) is a species-poor genus (3-4 species worldwide, all occurring in Israel) with an extreme infra-specific polymorphism. This polymorphism, combined with the taxonomic practice of describing species based one single specimens, has lead to innumerous descriptions of subspecies and varieties, which are presumably, at least in some cases, results of phenotypic plasticity within populations. Thus, the boundary between variation among populations and variation within populations has become too vague.

The genus Alyssum is extremely rich in species (170 worldwide, out of which 12 occur in Israel) and it is widespread in the temperate regions of the Northern Hemisphere. The floras of our region debate upon the identity of the species found in Israel. The main difficulties in the taxonomic assignment of specimens are the multitude of types that need to be studied and compared with collected material, as well as that the diagnostic attributes are commonly found in the very small and delicate flowers that commonly do not preserve well in common herbarium specimens.

In order to resolve the taxonomic difficulties in these genera we plan a comprehensive, country-wide floristic survey applying modern demographic and geographic approaches and targeting to the special features of the studied genera. We hope to obtain a clearer view of the diversity of crucifers and on their natural history in the country's unique landscape diversity.