Plants will survive by adapting to their environment, take for instance, cactus that survives in desert with little soil or water. Some plants are evergreens, which mean because of their folliage which retains a lot of heat from the sun, can continue to survive in high altitudes because sun does most of the feeding. If you go to extremely high altitudes, totally high mountains, then nothing, no plants, no people no animals can survive. It all depends. That is why we have such a diversity in plants all over planet, they adapt.