First Flower the Flowering Plants

Geology Video: First Flower The flowering plants (angiosperms), also known as Angiospermae, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms (conifers, cycads, Ginkgo) and can be distinguished from the gymnosperms by a series of synapomorphies (derived characteristics). These characteristics include flowers, endosperm within the seeds, and the production of fruits that contain the seeds. Etymologically, angiosperm means a plant that produces seeds within an enclosure; they are fruiting plants, although more commonly referred to as flowering plants. 1. Flowering plants are essential for human _____________________. 2. A team of paleontologists and paleobotanists led by Sun Ge of Jilin University, China, and David Dilcher of the Florida Museum of Natural History, University of Florida, recently announced the discovery of a new basal angiosperm family, Archaefructaceae. The new family is represented only by the two species, Archaefructus liaoningensis and A. sinensis. Five virtually complete fossils of these plants, including flowers, seeds, and fruits, were found in the Yixian Formation in Liaoning, northeastern ______________________. 3. One of Sun Geʼs students found a surprising fossil plant in that same formation that Sun Ge had been searching through for 10 years. Sun Ge brought the fossil to University of Florida where David Dilcher resided. According to Dilcher, probably _______________ percent of the plants humans are in contact with are flowering. 4. One of the best places on Earth to see the results of the evolution of flowering plants is the Hengduan Mountains in southwestern __________________, which span the regions of Sichuan, Hunan and Tibet. This is the most biodiverse temperate forest in the world. But to a plant lover it feels strangely familiar, because this is where many of the flowers in your garden came from. Professor Yin Kaipu, a botanist from Chengdu, has spent his life studying the diversity of plants in the Hengduan Mountains. Finding and cataloguing plants is essential to answering that question. While Sun Ge and Dilcher are studying evolution from the ancient fossil record, Yin is taking a different path. He is documenting the outcome of that evolution through a catalogue of _________________ plants. As part of that effort, Professor Yin has been joined by Dan Hinkley, an American plant explorer. 5. Half a world away the Hengduan Mountains, there is another kind of safety deposit box of plant diversity, David Dilcher's fossil collection at the Florida Museum of Natural History. These drawers hold over a quarter million fossils and document the evolution of plant life on Earth. The fossil record shows that, while flowering plants evolved rather late, they came to __________________ the Earth. 6. But clarifying the steps of flowering plant evolution has been difficult, in part because most plants decompose before they ever become a fossil. Usually only fragments remain, which is one of the things that makes this strange new fossil from China so extraordinary. The details of the plant are beautifully preserved. Sun Ge named it Archaefructus, which refers to the fossil's ancient ________________________. But how ancient is Archaefructus? 7. The first flowering plants didn't resemble any flowers we know today. They didn't have petals, they didn't have fragrance, they weren't beautiful. They simply were functional. To understand why this fossil that looks nothing like a flower could be one of the world's first, you have to understand what the function of flowers is. Flowers are all about ___________________. 8. To illustrate the basic sex life of a flower, we can use a lily. There are, of course, the recognizable petals, but at its center are the real stars: the stamens are the __________________ parts that produce pollen; the pistil is the female part that contains the _______________________. 9. The story of flower evolution is integrally linked with that of its pollinators, like insects and birds. This co-evolution has been largely responsible for their remarkable diversity. It is believed that there may be as many as _______________ different species of flowering plants, including things as different as roses, wheat and even apple trees. 10. Outside of London is one of the world's largest herbariums, or library of dried plants. Peter Crane is a leading paleobotanist and the former director at Kew. Inside this building we have somewhere between seven- and eight million herbarium specimens that represent the diversity of life, botanical life, on this planet. At the heart of this collection are the type specimens, the first plant collected of a type, the example that defines the species. One shown was of special interest because it was collected by _____________________ on the voyage of the Beagle. 11. At the time of Darwin, when he examined the record of the earliest flowering plants, he found there was a time when there were no flowering plants, and then suddenly there was a time when flowering plants were there, and they were full-formed. And he expressed it as an "abominable ______________________." 12. Else Marie Friis, a leading paleobotanist in Stockholm, has analyzed Archaefructus, as well, and disagrees with Dilcher and Sun Ge. Friis believes that Archaefructus shows signs of having adapted to live in the water, which would mean that it is a more ___________________ plant, and not the first flower. She has found flowers, millions of years old, that are, in effect, still in bloom. In very special sediments, these tiny flowers had turned into charcoal and were preserved intact. The oldest of these tiny flowers has been found to be 120 million years old. For Archaefructus to be the first flower, it must be older. 13. Sun Ge and Dilcher dated Archaefructus at just over 140 million years old, based on the other fossils found in this area. This put it in the Jurassic period, the age of _______________________. No one had ever found a flowering plant from the Jurassic period. 14. Leo Hickey, at Yale University, has taken another approach to tracing the first flower. He looks at leaves and pollen. Pollen can be found in many, many sediments. The pollen evidence was the nice dating tool. Seeing the intricate details of individual pollen grains allowed scientists to identify the distinctive pollen from flowering plants and then figure out when that pollen began showing up on Earth. Their answer? The very earliest flowering plant pollen shows up in rocks, which are of _________________________ age, which is about 134 million years in this case. 15. How could Archaefructus be almost 10 million years older than any known flowering plant pollen? The only sure way to find out was to date the earth that encased Archaefructus. A team from Berkeley, California, and China measured the radioactive decay in minerals from the fossil site. The results were not what Sun Ge and Dilcher had hoped for. The new evidence moved the fossil's age from 144 million years old to _________________ million, which was more in line with the pollen evidence. This still means that Archaefructus is the oldest known complete flowering plant fossil, but it moved it from the Jurassic period to the early Cretaceous. 16. Just a few blocks away from the fabled herbarium at Kew Gardens, scientists have a new tool to sort this all out. Today, ______________________ material, or DNA, from living plants is helping to build a more accurate family tree. The closer the DNA sequence, the closer the evolutionary relationship of two plants, which then allows them to group similar plants into related families. 17. The molecular evidence allows us to really understand living plants in enormous detail. What it doesn't allow us to do is to account for all the diversity that's extinct. Archaefructus is an example of this. We don't know where it would fit in the new molecular tree because we do not have its ____________________..

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