page_title: Flora of the Sierra Nevada alpine zone
section_title: Environmental conditions influencing flora
hierarchical_section_title: Flora of the Sierra Nevada alpine zone / Environmental conditions influencing flora
caption_attribution_description: Dansk: Bæk-Stenbræk (Saxifraga rivularis) fotograferet ved klippekant med nedstrømmende smeltevand nær havnen i Upernavik, Grønland. English: Alpine Brook Saxifrage (Saxifraga rivularis) photographed near the port in Upernavik, Greenland. Français&#160;: Fleurs de Saxifrage des ruisseaux (Saxifraga rivularis). Photo prise à proximité du port d'Upernavik, au Groenland (Danemark).
context_page_description: 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. 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.
context_section_description: The alpine zone, or alpine fell-field, is above the tree line, generally at 11,000 to 11,500 feet (3,400 to 3,500 m) in the south, and 9,900 feet (3,000 m) to 10,500 feet (3,200 m) 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.
  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 35 to 40 inches (0.89 to 1.02 m) 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.
caption: Pygmy saxifrage (Saxifraga rivularis) can be found up to elevations of over 14,000 feet (4,300 m).
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