That angiosperms first evolved in the tropics likely explains why, with respect to measuring exposure to cold:

Question

Quizplus · Accepted Answer

Different mechanisms evolved independently in different lineages. The diversity of mechanisms for measuring exposure to cold in angiosperms suggests that they evolved independently in different lineages, rather than being a common mechanism shared by all angiosperms. The fact that angiosperms first evolved in the tropics further supports this idea, as exposure to cold would have been less of a selective pressure in those regions.

That Angiosperms First Evolved in the Tropics Likely Explains Why