Since sending my last message on this topic, I have visited a university
library and read the 20 page article by Davis and Jury on these two
species. It is quite clear from the article that the species are
distinct, morphologically, biochemically and biogeographically. They
did quite detailed analyses of the plants in herbaria and also visited
the plants in the wild. What is most interesting is the distribution.
I.lazica is confined to two regions: the northern end of the eastern
coast of the Meditteranean - that is from Turkey south about half way
down the coast. It is also found along the south east shore of the
Black Sea. It does not overlap in distribution with ungiucularis.
I. unguicularis, on the other hand, is also found in two regions. The
first is that of southern Greece, the Greek islands, and the associated
mainland of Turkey. Neither species has been found along the southern
coast of Turkey. It also occurs in North Africa in the Algerian
region. This species has some subspecies which occur in different parts
of this distribution.
I hope that this helps understand why the two species are distinct.
Ian, in Ottawa