Sympatric OR allopatric speciation
Sympatry
The development of new species within a population. Two Hebe sp living in the same location but with different chromosomal numbers could suggest the reproductive isolation of the two species by polyploidy or anueploidy.
Allopatry
Genetic isolation of populations due to factors such as mountain building, glaciation. Eg the initial mountain building separated some species and the new environmental conditions changed the selective pressures acting on the gene pools, resulting in different species after reproductive isolation, eg H.speciosa and H. cupressoides.