Aloes and Lilies of Ethiopia and Eritrea

32 ALOES AND LILIES OF ETHIOPIA
Fig. 17.
Afroalpine
vegetation -
Senaiti Plateau,
Bale floristic
region.
10. Riverine vegetation (RV)
Ethiopia has several major systems of rivers and
tributaries: Abay (Blue­Nile) (starting in north­west),
Awash (starting in central), Baro (starting in the west),
Omo (starting in central­west), Tekezze (starting in the
north), Wabi­Shebele (starting in the south­east).
Eritrea also has some major rivers such as the Anseba
and Barka rivers flowing north; the Gash and Tekeze
rivers on the border with Ethiopia flowing west into the
Sudan. The upper course of the Gash river is known as
the Mereb river. These rivers are not year round rivers
and do not run on a regular basis, but fed by seasonal
rains during the main rainy season http://www.eritrea.
be/old/eritrea­geography.htm). These rivers and their
tributaries have riverine forests and riparian woodlands
in areas below 1800 m. The riverine forest vegetation is
very variable, and the floristic composition is dependent
on altitude and geographical location. Characteristic
common trees in these forests are Acacia polyacantha
subsp. campylacantha, Ficus sycomorus, Salix subserrata,
Trichilia emetica, Diospyros mespiliformis,
Mimusops kummel, Syzygium guineense, Tamarindus
indica, Tamarix nilotica, Breonardia salicifolia, and
Phoenix reclinata. There is often a shrub layer, and lianas
and vascular epiphytes occur. The ground cover includes
grasses, ferns, and a few herbaceous dicotyledons. Lilies
are uncommon along the major rivers.
Most riverine and riparian habitats are probably to
narrow and strip­like to map at the scale of 1:2,000,000
and hence not mapped and marked, but on the original