I'm Ada Osprey Senior Librarian of the Eagle Eyed Explorer Club Years ago the club recruited me as one of its special agents codename Agent Osprey Most days you'll find me in the basement of the library organizing the atlases But I always keep my rucksack at the ready in case the club needs me for one of its urgent missions I never know when to expect a call 6 3 15 12 STAFF ROOM 1 2 6 8 7 5 4 3 11 12 9 Mission Checklist LIBRARY PLANTS 1 Explorer Field Notebook 1 Magnifying Glass 1 Binoculars 1 Agent Issue Fleshlight 1 Portable Time Machine 1 Sandwich peanut butter My latest mission is not only top secret but very dangerous so keep it hush hush The club has ordered me to file a report on the entire history of plants as soon as possible It looks like I'll need to go back millions of years in time 4
EXPLORATIONS EXPLORER PLANTS ON EARTH HAPPENED I'll need to fill out a Journal to keep track of my discoveries I'm also drawing up a Timeline to show the life story of plants from the ancient seas to the present day No time to waste Are you feeling brave Let's go 5
1 WHAT ARE PLANTS EAGLE EYED LIBRARY ALGAE Over millions of years plants have evolved from tiny strands floating in the ocean into some of the most gigantic living things in the world Am oak tree or a fern bush a cactus or a sunflower green fields covered with grass or jungles thick with vines plants grow in every environment on planet Earth Plants are essential to how life on Earth works providing food energy even the oxygen we breathe But how did all this start Where did plants begin Before the Plants Three billion years ago as the sun shone over the seas early life forms were flourishing underwater These ancient organisms were cyanobacteria The cyanobacteria were tiny made up of one single cell In an empty ocean with little else to feed on they had discovered a unique way to stay alive They absorbed the light from the sun to create the energy to survive This miraculous way of making energy is called photosynthesis It's the secret to how all plants survive today As time passed the cyanobacteria began to combine with other organisms The other organisms relied on the energy the cyanobacteria created Soon these organisms began to develop into a soggy seaweed called algae The cyanobacteria remained inside the algae's cells but in the form of a small green capsule called a chloroplast The chloroplasts absorbed the sunlight and used photosynthesis to create energy The energy gave the algae strength to grow Little by little over millions and millions of years new kinds of algae began to form which were stronger and more solid Photosynthesis continued to be the secret to their survival As we will discover these algae are the ancient ancestors of all the different kinds of plants growing on Earth today Cyanobacteria under the microscope 6
Adapting to New Surroundings Evolution is a process of change where over time organisms bodies adapt to their environments These changes help them to survive New generations may come into the world with bodies that differ slightly from their parents but these differences may give them a better chance of survival Such changes are called adaptations The ancient cyanobacteria evolved with an adaptation that enabled them to make energy from sunlight Then other living things absorbed the cyanobacteria and evolved into kinds of algae The algae still relied on the energy the cyanobacteria provided But over millions of years the ancient algae changed too Some kinds of algae eventually evolved into plants that we would recognize today On sunny tropical shores plants such as palms evolved with huge leaves They could absorb lots of sunlight to generate energy In deserts with little rain cactus plants evolved with sturdy bodies They could store essential water which is otherwise in short supply PLANT PROFILE OAK EXPLORER NOTES Different species can have different characteristics slightly English oak Quercus robur Turkey oak Quercus cerris Acorns Leaves Getting Organized To see the connections between living things scientists organize plants and animals into different groups The members of each group all share similar characteristics Scientists place all the plants that produce flowers into one of these groups They call the flowering plants group the angiosperms And they place all the oak trees into a smaller group called Quercus Even within a group there can be further differences as well To tell the different oak trees apart scientists divide the groups into species The turkey oak Quercus cerris is a species of oak tree that grows in the United States The English oak Quercus robur is a species of oak tree that grows in England Its leaves are a different shape from those of the turkey oak Their differences reflect how these species have evolved in ways that help them survive in their own environments Turn the page discover more about different types of to plants Adaptations help plants survive in different environments 7
