Final answer:
Plant mitochondria have the ability to decouple proton flow from ATP synthesis, allowing for thermogenesis in thermogenic flowers like the spadix of the eastern skunk cabbage. This process is similar to how certain cold-adapted animals generate heat using uncoupling in brown fat tissue mitochondria.
Step-by-step explanation:
The feature of plant mitochondria not found in vertebrate animals that allows thermogenic flowers like the spadix of eastern skunk cabbage to produce heat is the capability to decouple proton flow from ATP synthesis. In these plant mitochondria, the energy that would normally be used to make ATP is instead released as heat. This process is similar to the one used by certain animals that have developed uncoupling systems in brown fat to generate heat.
While animals use brown fat to create a heat-generating process, plants like the skunk cabbage use a similar mechanism involving their mitochondria to produce heat and attract pollinators or melt snow in their surrounding environment. This thermogenesis in plants is facilitated by specific proteins embedded in the plant mitochondrial inner membrane that allows for the return of protons to the matrix without the production of ATP, thereby releasing energy as heat.