Skunk cabbage!
According to Wikipedia: "Skunk cabbage is notable for its ability to generate temperatures of up to 15-35°C (59-95°F) above air temperature by cyanide resistant cellular respiration in order to melt its way through frozen ground, placing it among a small group of plants exhibiting thermogenesis."
Here's an NY Times tribute to the generally unsung, if not always unsmelled, plant: "Seduced By a Skunk Cabbage".