Palms are evergreen trees, shrubs or vines with an unbranched trunk and a crown of round leaves with parallel venation. They are more closely related to grasses than to deciduous trees, even though palms produce flowers, fruit and seeds like other types of trees. Palms are an ancient group of plants, with fossils dating back at least 85 million years. There are 2000-3000 species of palms, but most are not widespread, and propser only in areas with warm temperatures and high rainfall. Humans harvest palms for sugar, oil, fiber, canauba wax, fruits (such as dates), and seeds (such as coconuts).