An exploratory floristic survey of the genus Mimosa was conducted in 1993 to ascertain species diversity and their
spatial patterns of distribution in Peninsular Malaysia. A new species record of uncertain indigene, M.. quadrivalvis was
recorded for the first time in restricted localities along the roadsides in Pekan Darat and Bertam, Seberang Perai,
Gurun and Bedong  in Kedah  in addition  to widely distributed and seemingly  ubiquitous presence of M. invisa
Mart. ex. Colla and M. pudica L. The latter two species were mostly found in open, disturbed and derelict habitats,
agricultural areas and ex-mining  lands. Both species exhibited  largely  contagious and overdispersed distribution
patterns with positive peaks in pattern intensity values although regularity or underdispersed distribution patterns do
manifest in certain localities. The giant mimosa, M. pigra inhabited in clustered thickets, large pockets of lands in the
urban and sub-urban localities in the states of Penang, Perak, Kelantan, Kuala Lumpur and Negeri Sembilan. In other
states, M. pigra was confined to a few localities in smaller patches. Except for M. quadrivalvis, the other species of
Mimosa are serious weeds  in  the agricultural,  recreational and  residential and derelict areas. A key  to  the Mimosa
species is constructed along with brief descriptions on their morphology and ecology.