Short answers, pulled from the story.
Lucas Cranach the Elder created the painting titled Madonna under the fir tree for the Wrocław Cathedral in 1510. The artwork was later restituted to Poland in 2012 after a forgery was discovered because the copy was painted on a fir board while the original was crafted from lime wood.
Philip Miller established the genus Abies in 1754 and defined the type species as Abies alba. The number of species within this group has fluctuated over time, with Aljos Farjon accepting 46 species by 2017 and Z. Debreczy and I. Rácz treating the genus as containing 67 species in 2011.
Fir trees can reach heights of 40 to 60 meters and sometimes approach 100 meters with a single straight trunk. Their needle-like leaves are attached singly to the branches with a circular base and are normally twisted at the base so that the side with stomata faces downwards.
Firs are distributed around the Northern Hemisphere and are native across much of North America, Eurasia, Turkey, Syria, Morocco, and Algeria. They are introduced in Scandinavia and the British Isles, with Abies sibirica growing as far north as 67°N in Siberia and A. guatemalensis growing as far south as 15°N in Central America.
Pest groups affecting fir trees include adelgid bugs, aphids, bark beetles, clearwing moths, conifer twig weevils, caterpillars of some moths, nematodes, sawflies, spider mites, and spittlebugs. Diseases of firs include annosus root rot, cankers, and needle cast, all of which pose threats to the health of these trees.
Section Balsamea is found in northern Asia and North America, while Section Grandis is found in western North America to Mexico, Guatemala, Honduras, and El Salvador. Section Momi is found in east and central Asia and the Himalaya, and Section Amabilis is found in the Pacific Coast mountains in North America and Japan.