As I've said, there are big areas of rain-florest in Brazil that rarely see less than 38°C during the day. There are also big areas of savanna that stay around that temperature for half a year (the half that rains). The fact that there are also cooler areas does nothing to explain how plants survive on those both.
I do think it's quite likely that plants keep leaves bellow the environment temperature, I'd just like somebody that knows it to confirm it or not.
As I've said, there are big areas of rain-florest in Brazil that rarely see less than 38°C during the day. There are also big areas of savanna that stay around that temperature for half a year (the half that rains). The fact that there are also cooler areas does nothing to explain how plants survive on those both.
I do think it's quite likely that plants keep leaves bellow the environment temperature, I'd just like somebody that knows it to confirm it or not.