ECOTYPIC VARIATIONS OF SOME DESERT PLANTS GROWING IN VARIOUS HABITATS

Abstract

It has been found that palnts growing under different combinations of environmental factors, a multitude of ecological races has arisen. These ecological races are termed ecotypes. In the present study four species are investigated, namely : Zilla spinosa, Echinops spinosissimus, Pituranthus tortuosus and Stachys aegyptiaca.Such species have wide ecological and geographical amplitudes. The defined ecotypes of such species within the Egyptian deserts, may be defined as climatic-edaphic ecotypes The recognized ecotypes of Zilla spinosa include :

a) An annual ecotype growing during the growth season in Wadi El-Assiuti, Mokattam and Cairo-Suez deserts. b)Aperennial meso -xerophytic ecotype growing in the reclaimed deser land e.g . Wadi El-Assiuti and S. Sinai mountains. c)The common xerophytic ecotype growing in the various habitats of the Eastern desert. d) The xero - halophytic ecotype growingin dry fairly saline soils of Ain Sukhna and related desert soilsof Eastern, Red Sea & Sinai habitats . The common xerophytic ecotype also showed two sub-ecotypes or ecophenes growing in the sunny and shaddy Microhabitats e.g. of Wadi Hof. The recognized ecotvpes of Echinops spinosissimus include : a) The common erect xerophytic ecotype of a wide ecological amplitude growing in the Eastern, Red Sea and Sinia habitats. bThe xero-halophytic erect ecotype of ommon occurence in the Red Sea and Sinia coastal areas. c) The xero-halophytic prostrate ecotype of common occurence in the Western Mediterranean region of Egypt. The recognized ecotype s of Pituranthus tortousus also include: a) The common erect xerophytic ecotype of a wide ecological amplitude growing in the Eastern , Western Red Sea and Sinia desert habitats . b) The xero-halophytic prostrate ecotype of W & E Mediterranean regions of Egypt. Also, the recognized ecotypes of Stachys aegyptiaca in this work include: a) The common xerophytic ecotype of the Eastern desert e.g. of Wade Hof. b) The common meso-xerophytic ecotype of Sinai e.g. of Wadi El- Arish and Saint Catherine habitats.