It describes the key morphological characteristics that distinguish the two species. If you go through to the key itself you can find distinct descriptions of each species. The first line of each indicates that the new growth on each species is distinct and different. P. campechiana, "
Tree; young shoots finely sericeous, soon gla- brous,greyish-brown, finelycracked,lenticellate"
P. lucuma "young shoots puberulous to shortly pu- bescent, becoming glabrous, pale grey-brown, slightly roughened and scaling, lenticellate or not."
They are definitely very similar species and very closely related, which is why they are in the same section. This map even is a good representative of the distributions which is fun to ponder their evolutionary histories and the reason they are distinct species.
