these drain into larger wadis that eventually debouch into the plains below. Wadi Yahameib and Wadi Aidieb drain the north and northeast flanks of Gebel Elba and several species of Acacia form dense woods in their lower reaches, supported by the moisture from above. On its southern side the principal drainage is into Wadi Serimtai, which is characterized by open Acacia scrub.
The amount of available moisture is reflected in the flora and fauna on this mountain, which has the richest biodiversity of any area of comparable size in Egypt. A surprising number of the species found on Gebel Elba are not found anywhere else in Egypt and are mostly formed of Afrotropical elements for which this mountain is the northernmost limit. The flora consists of nearly