Abstract

The aim of this is investigation to shed light on two sub-families Caesalpinioideae and Mimosoideae, in Habiel Jabbar District, Lahej Governorate, Republic of Yemen, during January 2018 to August 2019. An introductory order deals with the most significant features of two sub-families, synonyms, local names, distribution in study area, in addition to an artificial key for distinguishing between species and genera of the two sub-families in studied area, and up-to-date nomenclature for all studied taxa are presented.
The present study revealed the existence of 16 species within 6 genera belonging to two sub-families. The largest sub-family is  Mimosoideae (11 species). This sub-family represents a high percentage 68.75% of the total species of the studied area. The greatest genera recorded were Acacia (8 sp.) and Senna (4 sp.), these genera represent 75% of the total species recorded in the studied area. The present results revealed that Acacia hunteri is endemic to the flora of Yemen. The vegetative and reproductive characters proved that they are with high taxonomic values in identification and classification at the level of species and genera. It was also noted that the number of leaflets and pinnate pairs, flowers in racemes of inflorescences either spike or head, colour of flower, straight or twisted or falcate velvety pubescent pod, were found to be useful in distinguishing the members of genus Acacia.