W adi Arar in the northern region of Saudi Arabia is one of the most
important Wadis of the Kingdom. The present study provides an analysis
of vegetation types, life forms, as well as floristic categories and species
distribution. A total of 194 species representing 30 families of vascular
plants were recorded. Compositae, Gramineae and Leguminosae were the
most common recorded families. Therophytes and Chamaephytes are the
most frequent life forms, indicating typical desert spectrum vegetation.
The distribution of species in the different sectors of the Wadi as well as
the phytochoria for the recorded species is provided. Eighty nine species
(45.88%) are typically bi-regional. Furthermore, about 105 species
(53.5%) are mono- and pluriregional taxa. The highest number of species
(135 or 69.59%) was recorded for annual plants, while the lowest number
of species (59 or 30.41%) was recorded for perennial, short perennial or
annual to biennial species.