Volcanoes

• Plantlife in Hawaii is located on a string of volcanoes, generated by a so-called "hotspot"--a rend in the Earth's crust from which magma flows surface-ward. As the overlying plate moves tectonically past the hotspot, a chain of progressively older volcanoes mark that passage. Hawaii's volcanic islands "age" from southeast to northwest; a young one, called Loihi or "long tail," lies some 3,000 feet beneath the ocean's surface and will eventually rear high enough to become the newest Hawaiian island.
  
  

Big Mountains

• By some measures, Hawaii boasts the biggest mountains in the world--as measured from their crustal base. While Mount Everest in the Himalaya is over 29,000 feet from foot to summit, the crown of Mauna Loa is some 56,000 feet above its base, which lies in a depression of the seafloor caused by the volcano's weight. Above sea level, the volcano is a more modest 13,680 feet high. Its neighbor, 13,796-foot Mauna Kea, is slightly higher when measured from sea level, but not so massive.
  
  

Plant Diversity

• The Hawaiian Islands are close to the center of the North Pacific, and are immensely farflung. This isolation partly explains their enormous botanical diversity. So does the variety of microclimates. The northeastern aspects of the islands, oriented against the prevailing northeast trade winds, receive heavy rainfall: Indeed, Mount Waialeale on the island of Kaua'i claims some of the highest annual precipitation in the world, on the level of better than 400 inches. On the leeward side of the islands, however, the mountains' rainshadow effect makes for much drier conditions--some places see under 20 inches of rain.
  
  

Mountain-top Plants

• The highest elevations of Mauna Kea are above timberline.mauna kea image by Chris Bibbo from Fotolia.com
  
  Hawaii's loftiest peaks actually support upper timberlines, which are widely scattered in the tropics. On Mauna Kea, as writer S.R. Arno notes in "Timberline" (1984), the mamani, a type of tree, peters out at some 10,000 feet, ceding the volcano's summit to rock, shrublands, heath and seasonal snowpack. Mamani seeds can survive long periods at sea, and so reach such isolated outposts as Hawaii by rafting on marine currents.