Which genus is found predominantly in the Southern Hemisphere, Acaena or Sparganium?
Acaena: Acaena is a genus of about 100 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs in the family Rosaceae, native mainly to the Southern Hemisphere, notably New Zealand, Australia and South America, but with a few species extending into the Northern Hemisphere, north to Hawaii ("A. exigua") and California ("A. pinnatifida"). Sparganium:  It is widespread in wet areas in temperate regions of both the Northern and Southern Hemispheres.
Acaena