What exactly does it mean when a plant has a scientific name
that specifies a vairety, for example Nothofagus solandri var.
cliffortioides, or when the name includes an "x", as in
Populus maximowiczii Henry x trichocarpa, Populus
xcanadensis, or "Crataegus x macrocarpa"?
All of these species are in the USDA Plants database (of plants
that occur in the US). There are > 6000 occurences of the string
" var. " ~500 occurances of " ssp. " and only a handful...