From what I’ve been able to discern, this is one of the few photographs online of Mimosa monancistra (I was also able to locate an image of a dried specimen). I’m always pleased to have uncommon or rarely-encountered plants on BPotD. In Mexico, the common name for this plant is una de gato, or cat’s claw (or catclaw).
The genus Mimosa, as currently recognized, has 712 accepted and provisionally accepted taxa, according to the International Legume Database and Information Service. Of those 712 taxa, just over 250 are marked as provisional, suggesting that the taxonomy surrounding the genus is confusing. Dr. Rupert Barneby, writing on the number of species of Mimosa in Brazil, noted that “it is unlikely that an end to discovery is in sight” (source). Dr. Barneby was referring to the number of narrow endemic species occurring on high-altitude islands of campo cerrado (savannah woodland) and campo rupestre (open rocky landscapes). The barriers to interbreeding between populations of these environments, combined with time and selection pressures, has led to many mountains having their own distinct species of Mimosa.
Mexico also has its share of endemic Mimosa species (including today’s plant), though the endemism found in Mexico is partly due to the selection pressures of different local soil conditions.