A floristic account on Raudhat Khuraim (Central Province), Saudi Arabia,

Abstract

Field trips were conducted from 1990 to 1999to a prominent "raudha" (meadow) in the Central Province of Saudi Arabia in order to study the vegetation and to present an up-to-date knowledge of its flora. The study area (Raudhat Khuraim), a wide and shallow depression, is one of the finest places in the entire arid and extra arid parts of the Arabian Peninsula due to its plant density and speciation. Raudhat Khuraim, a protected area from vehicular traffic, lies at the fringe of a stony and sandy desert in the North East of Riyadh city and acts as a refuge for Saharo-Arabian taxa during adverse climatic conditions. Since the area is in the middle of an arid region, the vegetation is largely seasonal with a high percentage (82%) of annual species that germinate and flower soon after the winter rains. A complete annotated flora of the Raudha is prepared for the first time, including 1 gymnosperm, 131 dicots and 21 monocots. The raudha and its neighboring regions are devoid of any endemic plants. However, at least one species, Delphinium orientale 1.Gay (Ranunculaceae), mainly of North African and Mediterranean origin, has been reported for the Arabian Peninsula on the basis of a single collection from Raudhat Khuraim. Simple keys and brief descriptions of species have been provided for easy determination.