Compliance of a biennial mullein (Verbascum sinaiticum Benth.) to erratic desert floods in the Negev highlands, Israel

Verbascum sinaiticum tends to establish temporary stands on wadi gravel beds, and these exhibit a contagious pattern of distribution. V. sinaiticum, which is native to the Afro-montane region, acquires a fugitive character in the Negev. Its seeds germinate mainly on the 3rd or 4th days after wetting. Optimal germination was obtained in continuous light at 25oC; a gradual increase in NaCl, up to 80 mM caused delay in germination and reduced the daily rate. Irregular fluctuation of the water regime and the unstable nature of the wadi beds are essential for establishment of V. sinaiticum. Flash floods are also necessary: they provide periodic reformation of the disturbed habitat, removal of potential competitors, dispersion of the seeds of V. sinaiticum and wash-out of excess salts. -from Authors