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一、引言七叶树起源古老,最早的七叶树木化石发现于印度的晚白垩纪至早古新世地层~①,距今6500万年。而在北美,最早的七叶树叶化石和果实化石见于美国的古新世地层~②。全世界现有七叶树属(Aesculus)种类28种,包括自然种18个、5个杂交种、5个变种。我国有11种,含3个变种~③。除七叶树(A.chinensis)和天师栗(A.chinensis var.wilsonii)广泛分布外,大部分种集中在以云南为中心的西南地区~④;这一地区也是世界七叶树属的分布中心之一。印度原产七叶树有印度七叶树(A.indica)
I. Introduction Aesculus The ancient origin, the earliest horse chestnut fossils found in India late Cretaceous to Early Paleocene strata ~ ①, dating back 65 million years. In North America, the earliest Aesculus fossil and fruit fossils found in the United States Paleocene ~ 2. There are 28 species of Aesculus in the world, including 18 natural species, 5 hybrids and 5 varieties. There are 11 kinds of our country, including 3 varieties ~ ③. Except for the broad distribution of A. chinensis and A. chinensis var. Wilsonii, most of the species are concentrated in the southwestern region centered on Yunnan. This region is also the major part of the world’s Aesculus One of the distribution centers. India native horse chestnut Indian horse chestnut (A.indica)