Does Centaurium or Eucalyptus have more species?
Centaurium: Centaurium (Centaury) is a genus of 20 species in the gentian family (Gentianaceae), tribe Chironieae, subtribe Chironiinae. Eucalyptus: Eucalyptus L'Héritier 1789 is a diverse genus of flowering trees and shrubs (including a distinct group with a multiple-stem mallee growth habit) in the myrtle family, Myrtaceae. Eucalyptus:  Members of the genus dominate the tree flora of Australia, and include "Eucalyptus regnans", the tallest known flowering plant on Earth. Eucalyptus:  There are more than 700 species of eucalyptus and most are native to Australia; a very small number are found in adjacent areas of New Guinea and Indonesia. Eucalyptus:  One species, "Eucalyptus deglupta," ranges as far north as the Philippines.
Eucalyptus