The discovery in China of fossil specimens of a flower called Nanjinganthus from the Early Jurassic suggests that flowers originated 50 million years earlier than previously thought.

Scientists have discovered the earliest flower specimens dating back to the Early Jurassic, more than 174 million years ago, a study in the open-access journal eLife reports.

Before now, angiosperms (flowering plants) were thought to have a history of no more than 130 million years. The discovery of the novel flower species,which the authors named Nanjinganthus dendrostyla,throws widely accepted theories of plant evolution into question, by suggesting that flowering plants existed around 50 million years earlier. Also, Nanjinganthus morphologically surprised all botanists, showing a variety of “unexpected” characteristics that challenge almost all evolutionary theories.

Fossilized blossoms of Nanjinganthus on the same rock slab. (Photo by courtesy of WANG Xin's group, NIGPAS)

Angiosperms are an important member of the plant kingdom, and their origin has been the topic of longstanding debate among evolutionary biologists. Many previously thought angiosperms could be no more than 130 million years old. However, molecular clocks have indicated that they must be older than this. Until now,there has been no convincing fossil-based evidence to prove that they existed further back in time.

“Researchers were not certain where and how flowers came into existence because it seems that many flowers just popped up in the Cretaceous from nowhere,” explains lead author FU Qiang, associate research professor at the Nanjing Institute of Geology and Palaeontology (NIGPAS), Chinese Academy of Sciences (CAS). “Studying fossil flowers, especially those from earlier geologic periods, is the only reliable way to get an answer to these questions.”

绿色经济增长是衡量绿色经济可持续发展的核心指标，是在现有国民经济产出的基础上，扣除了由于自然资源消耗和环境污染等因素引起的经济成本。因此，为了核算绿色经济增长，首先需要引入两个虚拟部门：能源恢复部门和污染治理部门，进行简单的计算之后编制出绿色经济增长表[14]116-120。绿色经济增长表中主要包含以下五部分：

从表1可以看出，青薯9号出苗率均在92%以上，株高在70～73 cm，表明在本试验条件下对出苗率和株高影响不显著。单株块茎重处理B最高，处理A最低。商品薯率处理B最高，处理D最低，而在产量相同的情况下商品薯率越高收益越高。

The team studied 264 specimens of 198 individual flowers preserved on 34 rock slabs from the South Xiangshan Formation - an outcrop of rocks in the Nanjing region of China renowned for bearing fossils from the Early Jurassic. The abundance of fossil samples used in the study allowed the researchers to dissect some of them and study them with sophisticated microscopy, providing high-resolution pictures of the flowers from different angles and magnifications. They then used this detailed information about the shape and structure of the different fossil flowers to reconstruct the features of Nanjinganthus dendrostyla.

Having made this discovery, the team now wants to understand the relationship between Nanjinganthus and other angiosperms, namely, whether angiosperms are either monophyletic - which would mean Nanjinganthus represents a stem group giving rise to all later species - or polyphyletic, whereby Nanjinganthus represents one of many lineages of angiosperms and has little to do with many later species.

The feature unique of an angiosperm is “angioovuly” - the presence of ovules (precursors of seeds)fully enclosed before pollination. In the current study,the reconstructed flower was found to have a cupform receptacle and ovarian roof thought to enclose the ovules / seeds. This was a crucial discovery,because the presence of these features confirmed the flower's affinity of an angiosperm. Although there have been reports of angiosperms from the Middle-Late Jurassic in northeastern China, there are characters of Nanjinganthus that distinguish it from these previously known specimens and suggest that it is a new genus of angiosperm.

A lateral view of the earliest flower known to humans, Nanjinganthus,manifests in the fossil. (Photo by courtesy of WANG Xin's group,NIGPAS)

An idealized reconstruction of Nanjinganthus (Photo by courtesy of WANG Xin's group, NIGPAS)

“The origin of angiosperms has long been an academic ‘headache' for many botanists,” says senior author WANG Xin, research professor at NIGPAS. “Our discovery has moved the botany field forward and will allow a better understanding of angiosperms, which in turn will enhance our ability to efficiently use and look after our planet's plant-based resources.”

（2）促凝增强剂投加量的确定。取3号样品加入AP2.0%、水泥20.0%及相应添加剂，CA投加量不同，考察固化改良后浸出液主要指标，试验结果见表7。通过数据分析可以看出，当CA加量达到5.0%时，改良固化后的COD值较低47.5mg／L、抗压强度较高，达到1.76MPa。再增加加量固化效果变化不大，因此选择CA投加量为5.0%。

Reference: The paper “An unexpected noncarpellate epigynous flower from the Jurassic of China” can be freely accessed online at https://doi.org/10.7554/eLife.38827. The contents, including text, figures and data, are free to reuse under a CC BY 4.0 license.