Many aspects of the history of flowering plants (angiosperms) remain mysterious. Evidence of the earliest angiosperms comes from fossilized leaves, stems, fruits, pollen, and, very rarely, flowers. In addition, there has been much study of modern plant morphology (structure) and genetics in order to determine which living species might be most closely related to the ancient ancestors of angiosperms. Despite intensive efforts for over 200 years, scientists have still not reached consensus on which type of plant was the ancestor to the angiosperms, and when and where the angiosperms first evolved. Indeed, Charles Darwin himself called the origin of the flowering plants an “abominable mystery.”

What type of plant was the ancestor to the angiosperms? Most botanists now agree that the flowering plants are monophyletic in origin, meaning that they evolved from a common ancestor. Some paleontologists have suggested that the common ancestor may have been a type of cycad (palmlike tropical plants). Other paleontologists maintain that the angiosperms may have evolved from seed-bearing ferns. Finally, analysis of the morphological traits of some primitive living plants suggests that the ancestor may have been related to the modern pines. The question of angiosperm ancestry remains unresolved.

The time and place of the first appearance of flowering plants have long been a topic of great interest. There is good fossil evidence that early angiosperms, including a number resembling modern magnolias, were present in the Early Cretaceous geologic period (more than 100 million years ago). Angiosperms became increasingly abundant during this period. Between 100 million and 65 million years ago, a period known as the Late Cretaceous, angiosperms increased from less than 1 percent of flora (plant life) to well over 50 percent. Many of the modern plant families appeared during this time period. In the Early Tertiary period which followed, angiosperms increased to comprise 90 percent or more of Earth’s total flora. Where did these successful plants first originate and spread from?

Analysis of the fossil leaf structure and geographic distribution of the earliest Cretaceous angiosperms has led many biogeographers to conclude that they evolved in the tropics and then migrated poleward. It is known that angiosperms did not become dominant in the high latitudes until the Late Cretaceous. Paleontologists have recovered fossil angiosperm leaves, sterns, and pollen from Early Cretaceous deposits in eastern South America and western Africa. These two continents were joined together as part of Gondwanaland, one of two supercontinents that existed at that time. The locations of these early angiosperm finds would have been close to the equator during the Early Cretaceous and are comfortable with a model by which angiosperms spread from the tropics poleward.

Not all botanists agree with an African-South American center for the evolution and dispersal of the angiosperms, pointing out that many of the most primitive forms of flowering plants are found in the South Pacific, including portions of Fiji, New Caledonia, New Guinea, eastern Australia, and the Malay Archipelago. Recent genetic research has identified the rare tropical shrub Amborella as being the living plant most closely related to the ancient ancestor of all the angiosperms. This small shrub, which has tiny yellow-white flowers and red fruit, is found only on New Caledonia, a group of islands in the South Pacific. Many botanists conclude that the best explanation for the large numbers of primitive living angiosperms in the South Pacific region is that this is where the flowering plants first evolved and these modern species are relics of this early evolution. Comparisons of the DNA of Amborella and many hundreds of species of flowering plants suggest that the first angiosperm arose and the development of separate species occurred about 135 million years ago.

Recently discovered fossils complicate our understanding of the origin of the angiosperms even further. Paleontologists from China have found beautifully preserved fossils of an angiosperm plant, including flowers and seeds, in Jurassic period deposits from China. The site, which is about 130 million years old, is near modern Beijing. The new fossil plant found at the site is now the oldest known angiosperm. The age of the fossils and the very primitive features of the flowers have led the discoverers to suggest that the earliest flowering plants may have evolved in northern Asia.

开花植物（花卉植物）历史的许多方面仍然是个谜。最早的花卉植物存在的证据来自于化石树叶、茎、果实、花粉以及极少数的花朵。此外，现今有大量的对现代植物形态（结构）和基因的研究，以此来确定哪种生物可能与被子植物的远古祖先最为接近。尽管经过了200多年的努力，科学家对于哪种类型的植物是被子植物的祖先以及被子植物第一次进化是何时何地的问题仍然没有达成共识。事实上，查尔斯•达尔文称开花植物的起源为“恼人之谜”。 被子植物的祖先是什么类型的植物？大多数植物学家认为开花植物的起源是单源的，这意味着它们是由同一祖先进化而来的。一些古生物学家认为这一共同祖先可能是一种苏铁属植物（掌状热带植物）。而其他的古生物学家坚持认为被子植物可能是由含种子的蕨类植物进化而来的。最后，对一些原始活体植物形态特点的分析表明被子植物的祖先可能与现代的松树有关系，但被子植物的祖先问题仍未解决。 开花植物第一次出现的时间和地点至今以来一直是热门话题。有力的化石证据表明，早期的被子植物包括一些类似现代木兰类植物存在于白垩纪地质时期（大约1亿多年前），被子植物的数量在此期间不断增长。在1亿年前和6500万年前之间的晚白垩纪时期，被子植物的数量从不到1%的植物群增长到了超过50%，此时，许多现代植物系也出现了。在接下来的早期第三纪，被子植物的数量增长到占地球总植物群的90%，甚至更多。这些生长繁茂的植物最初是从哪里起源和传播的呢？ 从最早的白垩纪被子植物的化石叶子结构和形态分布的分析中，许多生物地理学家得出了结论：被子植物是在热带地区进化，然后向南极移动。众所周知，被子植物在高纬度地区直到晚期白垩纪才占据了主导地位。古生物学家从南美洲东部和西非的早白垩世矿床中复原了化石被子植物的叶子，茎和花粉。这两大洲连接着，是当时存在的两个超大陆中的一个——冈瓦纳大陆的一部分。这些早期被子植物在早期白垩纪时的位置已经很接近赤道了，并且以这种舒适的方式从南极方向的热带地区向外生长。 并非所有的植物学家都赞同非洲—南美洲被子植物的演变和扩散中心说，这种观点指明许多最原始的开花植物在南太平洋被发现，包括斐济、新喀里多尼亚、新几内亚、澳大利亚东部和马来群岛。最近的基因研究发现稀有的热带灌木互叶梅属是与所有被子植物的远古祖先关系最近的活体植物。人们只在南太平洋的新喀里多尼亚的一群岛屿上发现了这种小型的灌木，它们有微小的黄白色花朵和红色的果实。许多植物学家推断，对南太平洋出现的大量原始活体被子植物最好的解释是这是开花植物首先进化的地方，这些现代物种是这种早期进化的“遗迹”。把叶梅属的DNA和数以百计的开花植物的DNA作比较表明，第一种被子植物的出现和不同物种的发展发生在约1亿3500万年前。 最近发现的化石使我们对被子植物起源的进一步理解变得复杂了。来自中国的古生物学家已经在中国侏罗纪时期的沉淀物中发现了完好保存的一种被子植物的化石，包括它的花朵和种子，该地点大约有1.3亿年的历史了，与现代的北京很接近。在该地发现的新的植物化石是现今已知的最古老的被子植物。发现人认为，从该化石的年代和其花朵最原始的特点看来，最早的花朵植物可能是在亚洲北部进化的。