Opaca basically means "shady" in Latin and is named so because it grows quite well in the shade.
ilex opaca
An American holly is a species of holly, Latin name Ilex opaca, native to the eastern United States.
The scientific or taxonomic name would be Ilex opaca.
ILEX
I'm pretty sure its the pine tree Ilex aquifolium is the Latin name for the European holly.
A yerba is a species of holly, Latin name Ilex paraguariensis, which is native to southern South America.
"Opaca" is a specific epithet used in Latin botanical nomenclature to denote a species with characteristics like being dark, opaque, or with little translucency. It often indicates a plant or animal that has a dark or obscure appearance.
google is good for this: http://images.google.com/images?um=1&hl=en&q=American+Holly+(Ilex+opaca)&btnG=Search+Images
A yerba mate is a species of holly, Latin name Ilex paraguariensis, native to southern South America.
The name would be Ilex spp.
Empis opaca was created in 1804.
Amorphoscelis opaca was created in 1908.