The Rutaceae family has 160 genera, more than I can wrap my little head around. The most economically significant of these by far is Citrus. Due to a long history of propagation and cross-breeding, the number of Citrus species is not cut and dry. Above, the famous Meyer lemon, Citrus x meyeri, named after Frank Nicholas Meyer -- an agricultural explorer for the USDA who brought the plant from China in 1908.
What can you say about citrus? There's no argument against it. It prevents scurvy and cures colds.
That being said, there is a remarkable variety of citrus plants, and keeping track of all the distinctions can be difficult.
One of the few non-Citrus members of the family I have encountered is Casimiroa edulis, or white sapote. The tree seen below grows on a street in the Salinas Valley, where evidently it is warm enough to support this native of Mexico and Central America. Not too surprisingly, the tree also goes by the name "Mexican apple".
