Species of pine trees in Chongqing

There are nearly 80 kinds of pine trees in the world. Although there are many kinds, the leaves are slender and needle-shaped, commonly known as pine needles. Most needles are gathered by one or several leaves. One needle single leaf pine is only distributed in Nevada and Mexico in the United States, belonging to a few varieties. Two-needle bundle of two-leaf pine is not only a wide variety, but also widely distributed, such as Pinus tabulaeformis and Pinus sylvestris var. mongolica. Pinus sylvestris var. mongolica, Pinus thunbergii and Pinus densiflora distributed in several provinces of North China and Northwest China, Pinus massoniana, Pinus taiwanensis, Pinus alpine and Pinus Bashan in Qinba Mountain area, and Pinus Taiwan Province and Pinus brevifolia in North America. Most of them are the main tree species for afforestation in barren hills in China. Three-needle and three-leaf pine includes Pinus bungeana, Pinus yunnanensis, Pinus Simao in Sichuan and Yunnan, Pinus elliottii and Pinus taeda introduced from central and southern China. A bundle of four-needle pine trees is rare and only distributed in California, USA. Besides, eggs and pine are in bundles of four or five needles. There are many kinds of pine trees with five needles in a bunch, which are widely distributed, including Korean pine in the northeast, Huashan pine, Qiao pine, Guangdong pine in the northwest and southwest provinces, Anhui five-needle pine, Dabie mountain five-needle pine, Chinese pine and Taiwan Province fruit pine. The difference of pine needles helps us to classify and identify pine trees and understand their ecological characteristics. Usually, five-needle pine is suitable for humid environment and has strict requirements on soil, while two or three-needle pine is more drought-tolerant and can grow in thin soil. For example, a bunch of Pinus tabulaeformis with two needles has strong adaptability to land climate and atmospheric drought, and of course it also sags with its needle pores. Wax on the leaf surface can reduce partial evaporation.