American oaks stop one degree short of equator
Flora de la Real Expedición Botánica del Nuevo Reino de Granada (1783–1816), vol. XIV, p. 26 Panama is just about where the southward journey of the oak through the Americas stops. While the closing of the isthmus between North and South America between 3.5 and 5 million years ago allowed oaks into a small area of north-western South America, only one species extends into Colombia. Which means oaks barely have a toehold in South America, and never cross the equator. They get close, to about one degree of latitude north. After splintering into some 240 species, the oaks of the Americas end their conquest and evolution in the Americas with Andean oak, a species named by French botanist Aimé Bonpland to honour his travelling companion and German – let’s say – natural philosopher extraordinaire, Alexander von Humboldt. Hence Quercus humboldtii . Monsieur Bonpland and Herr Humboldt travelled through these parts between 1799 and 1804, with Bonpland describing twenty new species of Quercus