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The flora of the U.S. Sierra Nevada alpine zone is characterized by small, low growing, cushion and mat forming plants that can survive the harsh conditions in the high-altitude alpine zone above the timber line.〔Wildflowers of the Eastern Sierra and adjoining Mojave Desert Great Basin, Alpine (section), Laird R. Blackwell, 2002, Lone Pine Printing, ISBN 978-1-55105-281-6〕〔〔 These flora often occur in alpine fell-fields. The Sierra Nevada alpine zone lacks a dominant plant species that characterizes it, so may or may not be called a vegetation type. But it is found above the subalpine forest, which is the highest in a succession of recognized vegetation types at increasing elevations.〔〔 Botanists have ranked the Sierra Nevada alpine zone floral bloom as one of California's foremost wildflower displays, with flowers of fantastic color and abundance. Many of the alpine species are notable for large and showy flowers, which must compete for the pollinators during brief growing seasons.〔 Botanist Philip A. Munz wrote, "These natural rock gardens are spectacular sights when in full flower."〔 Botanist Laird R. Blackwell wrote, "Up here... the flowers seem to glow... perhaps only the flowers of the harsh desert can rival the alpine flowers for intensity."〔 Over 90% of California's alpine flora are perennial herbs.〔 Annuals are not common.〔 Depending on the elevation used to define its lower boundary, the Sierra Nevada alpine zone may have almost 600 species, about 200 of which are only found here (endemic). The flora includes plants that are descended from the plants that survived the glaciation of the last ice age (relict plants), because they were growing on mountain peaks that stood above the ice sheets like islands.〔 ==Envoronmental conditions influencing flora== The alpine zone, or alpine fell-field, is above the tree line, generally at in the south,〔〔 and 〔 to 〔 in the north. The plants are influenced by having to endure long and very cold winters, poor to no soils, constant high winds, intense sunlight, and a short cool and dry growing season in the summer, that lasts only about 6–8 weeks.〔(【引用サイトリンク】work=National Park Service Ranger class )〕 Winds are strong and constant.〔 The constant wind makes unsheltered areas colder than sheltered spots, depositing snow in some places, while scouring the snow out of other locations.〔 The constant wind increases loss of water from the plants to the atmosphere (transpiration).〔 Sunlight is intense.〔 Soils are thin and rocky, or absent.〔 Soils are low in moisture.〔 Rainfall is rare.〔 Almost all of the of annual precipitation falls as snow, and growing season can be as short as just days. Annual plants must quickly grow to maturity, and all plants must quickly flower and develop mature seed.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Flora of the Sierra Nevada alpine zone」の詳細全文を読む スポンサード リンク
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