Morphology and Distribution of Three Genera of Amaranthaceae in the South Western Area of Saudi Arabia

Department of Biological Sciences, Faculty of Science, King Khalid University, Abha, P. O. Box 9004, Saudi Arabia.Four species (Aerva javanica, A. lanata, Pupalia lappaceae and Achyranthes aspera) representing three genera of the family Amaranthaceae, and commonly distributed in the south western part of Saudi Arabia, were investigated. The study involved the morphological characteristics and their distribution in relation to some environmental parameters (altitude, temperature and rainfall). The data indicated a great morphological similarity between the two Aerva species, with little differences which could be correlated to their distribution in the area. Aerva javanica species has a wide distribution in all habitats, while Aerva lanata was found to be restricted only to high altitudes and low temperature. On the other hand, considerable morphological differences were observed between Pupalia lappaceae and Achyranthes aspera and the two Aerva species. Pupalia lappaceae and Achyranthes aspera were found to be restricted to the presence of water with preferences to high altitudes. In conclusion, the distribution of the four Amaranthaceae species under study in Aseer area is associated clearly with several factors. These include in the first rank the morphological adaptation of the plant species to its habitat. In addition to the environmental parameters; e.g. altitude, temperature and rainfall which influence the distribution, establishment, growth and regeneration of the plant species