词条 | Douglas fir |
释义 | Douglas fir tree ![]() The North American tree commonly known as Douglas fir is P. menziesii (P. douglasii by some authorities). It has several forms, one with reflexed bracts, that sometimes are considered to be separate species. Douglas fir may grow to 75 m (250 feet) tall and 2.4 m in diameter. It is one of the best timber trees in North America, as well as a popular ornamental and Christmas tree, and is used for reforestation along the Pacific Coast. The first seeds are produced at about 25 years, with large crops every 5 to 7 years. The bigcone Douglas fir (P. macrocarpa), a smaller species important only for erosion control, bears cones 10 to 15 cm (about 4 to 6 inches) long. |
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