Tropical flowers such as plumeria, orchids, hibiscus, red ginger, heliconia, and anthuriums grow wild on all islands. Pikake blossoms make the most fragrant leis, and fragile orange ilima (once reserved only for royalty), the most elegant leis. The lovely wood rose is actually the dried seed pod of a species of morning glory. Mountain apple, Hawaiian raspberry, thimbleberry, and strawberry guava provide refreshing snacks for hikers; and giant banyan trees, hundreds of years old, spread their canopies over families picnicking in parks, inviting youngsters to swing from their hanging vines. Sprouting ruby, pompom-like lehua blossoms - thought to be the favorite flower of Pele, the volcano goddess - ohia trees bury their roots in fields of once-molten lava. Also growing on the Big Island as well as the outer slopes of Maui's Haleakala, exotic protea flourish only at an elevation of 4,000 ft; while within Haleakala's moonscape crater, the rare and otherworldly silversword - a 7-ft stalk with a single white spike and pale yellow flower found nowhere else on earth - blooms once and then dies.