Haloxylon salicornicum and Salsola imbricata (Chenopodiaceae)
are perennial shrubs widely distributed in sandy habitats of the
Arabian deserts. Both species are succulent halophytes and welladapted
to endure severe environmental stresses and human
disturbances in the deserts. H. salicornicum has been considered
one of the most promising species for re-seeding deteriorating
desert range vegetation and for sand dune fixation [7]. In addition,
S. imbricata has the ability to stabilize sand dunes and to restore
degraded, oil-polluted soils [8,9].
Both H. salicornicum and S. imbricata ripen and shed their seeds
early in the growing season (early winter). This coincides with the
onset of suitable conditions for germination and seedling establishment
(e.g., availability of rainfall and lower temperatures) are optimum
for germination and seedling establishment). Shortly after
effective rainfalls, many seedlings appear under and around the
maternal plants (Ali El-Keblawy, unpublished data). Under laboratory
conditions, fresh harvested seeds of both species germinate
to a very high level with high speed [10,11]. Seed bank studies indicated
that a transient nature of the seed bank both in S. imbricata
[12,13] and H. salicornicum