摘要
全球藜科植物共约130属1500余种,广泛分布于欧亚大陆、南北美洲、非洲和大洋洲的半干旱及盐碱地区。它基本上是一个温带科,对亚热带和寒温带也有一定的适应性。本文分析了该科包含的11族的系统位置和分布式样,以及各个属的分布区,提出中亚区是现存藜科植物的分布中心;原始的藜科植物在古地中海的东岸即华夏陆台(或中国的西南部)发生,然后向干旱的古地中海沿岸迁移、分化,产生了环胚亚科主要族的原始类群;起源的时间可能在白垩纪初,冈瓦纳古陆和劳亚古陆进一步解体的时期。文章对其迁移途径及现代分布式样形成的原因进行了讨论。
: Numbers of species and genera, endemic genera, extant primitive genera, relationship and distribution patterns of presently living Chenopodiaceae (two subfamilies, 12 tribes, and 118 genera) are analyzed and compared for eight distributional areas, namely central Asia, Europe, the Mediterranean region, Africa, North America, South America, Australia and East Asia.
The Central Asia, where the number of genera and diversity of taxa are greater than in other areas, appears to be the center of distribution of extant Chenopodiaceae. North America and Australia are two secondary centers of distribution.
Eurasia has 11 tribes out of the 12, a total of 70 genera of extant chenopodiaceous plants, and, it contains ,the most primitive genera of every tribe. Archiatriplex of Atrip-liceae, Hablitzia of Hablitzeae, Corispermum of Corispermeae, Campharosma of Camphoros-maea, Kalidium of Salicornieae, Polecnemum of Polycnemeae, Alexandra of Suaedeae, and Nanophyton of Salsoleae, are all found in Eurasia. The Beteae is an Eurasian endemic tribe, demonstrating the antiquity of the Chenopodiaceae flora of Eurasia. Hence, Eurasia is likely the place of .origin of chenopodiaceous plants.
The presence of chenopodiaceous plants is correlated with an arid climate. During the Cretaceous Period, most places of the continent of Eurasia were occupied by the ancient precursor to the Mediterranean, the Tethys Sea. At that time the area of the Tethys Sea had a dry and warm climate. Therefore, primitive Chenopodiaceae were likely present on the beaches of this ancient land. This arid climatic condition resulted in differentiation of the tribes Chenopodieae, Atripliceae, Comphorosmeae, Salicornieae, etc. , the main primitive tribes of the subfamily Cyclolobeae. Then following continental drift and the Laurasian and Gondwanan disintegration, the Chenopodiaceae were brought to every continent to propagate and develop, and experience the vicissitudes of climates, forming the main characteristics and distribution patterns of recent continental floras.
The tribes Atripliceae, Chenopodieae, Camphorosmeae, and Salicornieae of recent Chenopodiaceae in Eurasia, North America, South America, southern Africa, and Australia all became strongly differentiated. However, Australia and South America, have no genera of Spirolobeae except for a few maritime Suaeda species. The Salsoleae and Suaedeae have not arrived in Australia and South America, which indicates that the subfamily Spirolobeae developed in Eurasia after Australia separated from the ancient South America- Africa continent, and South America had left Africa. The endemic tribe of North America, the tribe Sarcobateae, has a origin different from the tribes Salsoleae and Suaedeae of the subfamily Spirolobeae. Sarcobateae flowers diverged into unisexuality and absence of bractlets. Clearly they originated in North America after North America had left the Eurasian continent. North America and southern Africa have a few species of Salsola, but none of them have become very much differentiated or developed, so they must have arrived through overland migration across ancient continental connections. India has no southern African Chenopodiaceae floristic components except for a few maritime taxa, which shows that when the Indian subcontinent left Africa in the Triassic period, the Chenopodiaceae had not yet developed in Africa. Therefore, the early Cretaceous Period about 120 million years ago, when the ancient Gondwanan and Laurasian continents disintegrated, could have been the time of origin of Chenopodiaceae plants.
The Chinese flora of Chenopodiaceae is a part of Chenopodiaceae flora of central Asia. Cornulaca alaschnica was discovered from Gansu, China, showing that the Chinese Chenopodiaceae flora certainly has contact with the Mediterranean Chenopodiaceae flora. The contact of southeastern China with the Australia Chenopodiaceae flora, however, is very weak.
出处
《植物分类学报》
CSCD
1996年第5期486-504,共19页
Acta Phytotaxonomica Sinica
基金
国家自然科学基金
关键词
藜科
起源
分化
地理分布
Chenopodiaceae
Origin
Differentiation
Distribution
