棕榈科植物的地理分布

THE GEOGRAPHIC DISTRIBUTION OF THE PALMAE

棕榈科是一个泛热带分布的科，共有１９８瞩，约２６７０种，下分６亚科，１４族．贝叶棕族是最原始的族．低地榈族则最进化．本科植物在世界上的分布可划分为１３个区，其中以印度─马来西亚区和新热带区的属、种最多．中国只有１６属和８５种，没有特有属．这些种大部分属热带亚洲分布，与热带亚洲植物区系关系非常密切．关于棕榈科起源地问题，有西冈瓦纳起源和劳亚起源之说．根据化石记录和形态特征的分析，棕榈科很可能于早白垩纪起源于西冈瓦纳古陆．这些植物在起源地发生之后．沿着４条路线向欧洲、北美洲、亚洲（南部、东部和东南部）和澳大利亚扩散．

The Palmae is a pantropic family comprising 198 genera and 2670 species of six subfamilies and fourteen tribes. Among them the Trib. Corypheae is considered as the most primitive one of the family, on the contrary the Trib. Geonomeae is the advanced one.According to Takhtajan's division of floristic regions of the world,the family occurs in thirteen regions including subkingdom or kingdom (see table 1. ), viz. Eastern Asiatic Region, North American Atlantic Region, Mediterranean Region, Madrean Region, African subkingdom, Madagascan subkingdom, Indomalesian subkingdom, Polynesian subkingdom, Neocaledonian Region, Neotropical kingdom,Northeast Australian Region, Fernandezian Region and Neozeylandic Region. The Indomalesian subkingdom and Neotropical kingdom are the greatest concentration of genera and species.There are sixteen genera and eighty-five species of the family in China. According to Wu ZhengYi's 'The Areal-Types of Chinese Genera of Seed PlantS', the distribution of this family may be sorted into five areal types, i. e. Tropical Asia, Africa (or East Africa, Madagascar) and Australasia disjunction ; Tropical Asia and Tropical Australasia; Tropical Asia to Tropical Africa, Tropical Asia (IndoMalesia) ; and East Asia. Although there is no endemic genus of Palmae in China, of the 16 genera occur in China, 9 belong to Tropical Asia and the East Asia, occupying 56. 2% of the total genera..This shows that the Palmae of China is closely related to Tropical Asia and becomes a pet of its total.As for the origin of Palmae, there are two different views, i. e. from West Gondwanaland (Moore, 1973a) or from Laurasia (Uh1 and Dransfield, 1987). The fossil records and the analysis of morphological characters have shown that, firstly, the most primitive taxa of the family belong to genera Trithrinax, Chelyocarpus and Cryosophila of Coryphoideae, growing in South America at 10° N30° S; Secondly, Calamoideae and Phytelephantoideae are considered parallel with Coryphoideae in evolution. Some genera of them such as Laccosperma, Eremospatha and the three genera of Phytelephantoideae are not only the least specialized genera but also existing in West Africa or the Congo Basin and in west or northwest of South America. It seems reasonable to presume that the West Gondwanaland or the regions of South America at 10° N to 30° S and Africa at 15°N to 15° S are the centers of origin of Palmae for the greatest concentration of primitive taxa.The fossil records show that the time of origin of Palmae may dates from early Cretaceous period.The fossils indicate that since the occurrence of palmaceous plants in the West Gondwanaland,they had been firstl developed and followed by dispersal along four routes, i. e. Europe-GreenlandNorth America, South Asia-Southeast Asia or East Asia, India-Southeast Asia or Australia, and Antarctica-Australia routes, and later reached Central America through South America.