Some species of pine are fire-adapted, and their cones won't open until exposed to temperatures in the the neighborhood of 300 degrees Fahrenheit.
For an exam, one of my Botany professors gave us a pine cone to identify. From its characteristics, it
looked like it came from a Pond Pine (
Pinus serotina), but the instructor assured us that he'd plucked it fresh from a tree just yesterday. Since the cones of this species will not normally open when fresh and resinous unless exposed to high temperatures, and since there had been no fires in the vicinity recently, I reasoned that though it
looked like Pond Pine, it must be something else. So, I put down my alternate choice as the correct answer.
I was, of course, wrong -- it
had been a cone from a Pond Pine. When I asked the instructor how that could possibly have been a fresh cone from a Pond Pine, he replied, "I put it in the oven."