When tulip trees first evolved, atmospheric CO₂ levels were falling from about 1,000 parts per million (ppm) to 500 ppm.

T he tulip tree, Liriodendron tulipifera, is a large deciduous tree native to North America. The tree gets its name from the shape of its blooms, which appear tulip-like when they begin to open.

The tulip tree is a close relative of the magnolias, but its wood does not fit neatly into the softwood or hardwood categories. Instead, its macrofibrils had a diameter of about 22 nm ...