Ackerman's (1973) work, however, involved the
three species, C. kissi, C. oheifera and C, sasan qua,
whose taxonomy has since been revised (Chang &
Bartholomew, 1984). In the present study, C. kissi
grouped closely with C. sasanqua (see Fig. 1),
although both are now classified in sections Paracamellia
and Oleifera, respectively. Although species
of section Theopsis also grouped closely, crosses
within the section are often difficult, reflecting
behaviour typical of cenospecies and suggesting the
existence of genetic isolation barriers usually associated
with more distant crosses (Ackerman, 1973).