1 . Lichens (地衣)
Lichens look like splashes of paint left behind by a careless painter. Unlike many plants, they do not require soil to grow. They grow on trunk of trees in steaming tropical rain forests, on farmers’ fenceposts, on the bricks of big-city buildings, and on old gravestones. Lichens can tolerate extremes of climate. They grow on rocks in hot springs, on wind-swept mountaintops, and on stones in the driest deserts. In the Arctic, lichens are the principal source of food for reindeer. Whole mountainsides in Antarctica appear green and orange because of the presence of lichens; they are one of the few plants that can survive there. They are among the oldest of known plants. Recently, scientists discovered lichen fossils on a rock in a mine in southwest China that date back 600 million years.
When conditions become harsh, lichens become dormant (休眠). If there is not enough moisture, they simply dry up, but a short rain or even a heavy dew gives them new life. When growing on rock surfaces, lichens produce acids that dissolve (溶解) the minerals, contributing to the process of weathering by which rocks are slowly turned to soil. This property enables lichens to be pioneers. They appear on barren rock rubbed clean by glaciers, fires, lava flows, or floods, beginning the process of soil formation that allows mosses (苔藓) and other plants to later take root. But, despite their hardiness, lichens are extremely sensitive to airborne particles(颗粒). That’s why they serve as an early warning system for air pollution.
It is the acids lichens produce that give them their distinctive colors. Lichens are often spoken of in the same breath as mosses, and some lichens are even called mosses, but true mosses are all distinctively green, whereas lichens appear in many vivid colors. At one time, acids from lichens were used to make dyes, such as the purple dye, the blue dye, and the red dye, and they are sometimes still used that way today. Some lichens, such as oakmoss, contain oils that produce fragrant odors used in scented soaps, cosmetics and perfumes. Some lichens are also known to have antibiotic properties to kill bacteria.
So definite are the form, color, and characteristics of these organisms that for hundreds of years lichens were constantly under scientists’ microscope.
1. What characteristic of lichens is mainly talked about in paragraph 1?| A．They grow only on rock surfaces. |
| B．They live primarily in cold places. |
| C．They have adapted to a wide variety of environments. |
| D．They live in remote locations far from human communities. |
| A．have their primitive structure |
| B．grow in areas before other plants do |
| C．are found in remote parts of the world |
| D．develop so early in the history of the planet |
| A．as a means of coloring clothing |
| B．as a type of medicine |
| C．as a source of food |
| D．as an ingredient in perfume |
| A．Lichens are important in Canada because of their abundance in the north. |
| B．Extracts of lichens were sold as herbal medicines to facilitate hair growth. |
| C．Glacier Park’s vast array of lichens indicate relatively good air quality. |
| D．A German botanist first found lichens are composed of two life forms. |
Bamboo has been planted in China for thousands of years at least. And it is possibly one of the most
The bamboo sea in southern Sichuan is the
Among them, the Nan bamboo
There is bamboo scenery, mountains and rivers, lakes, ancient temples, as well
3 . The Royal Botanical Gardens, Kew, in the UK, are home to thousands of fascinating plants, but none are as lonely as the Encephalartos woodii, an ancient cycad (苏铁门植物) species and, most likely, the last one of its kind.
It was in 1895 that botanist John Wood noticed this interesting looking palm tree on a steep slope in southern Africa. Spellbound by its multiple trunks and arched palm fronds (苏铁类植物的叶), Dr. Wood —who made his living collecting rare plants — had some stems removed and sent to London in a box. It ended up in the Palm House at the Royal Botanical Gardens, where it has been waiting for a mate for over a century. Despite numerous efforts to find it a mate, the Encephalartos woodii at Kew remains alone, unable to produce an offspring (后代) and reproduce its species. For this reason, many consider it the world’s loneliest plant.
Two hundred million years ago, when dinosaurs still roamed the world, cycads were everywhere. They made up around 20% of plants, acted as shelter for some dinosaur species and as food supply for others. They managed to somehow survive five ice ages, adapted to coexist with new species of plants, but as time passed, their numbers dwindled. Like all other cycads, Encephalartos woodii went from numbering millions of specimens, to thousands, and today, possibly just one, a male.
Some plants have both male and female organs, but not Encephalartos woodii. Without a female specimen to produce the seeds, it can never mate.
The Encephalartos woodii is technically not the last of its kind. It has been cloned several times, and its clones can be found in several botanical gardens around the world. It can even mate with some closely related species, but it can’t produce a true offspring. It just sits there, the last of its ancient species waiting for a female species to be found somewhere on Earth. "Surely this is the loneliest organism in the world," biologist Richard Fortey once wrote, "growing older, alone, and fated to have no successors. Nobody knows how long it will live. "
1. What can we learn about the Encephalartos woodii?| A．It has been the last of its species for centuries. |
| B．It once was a common being with male and female organs. |
| C．Scientists’ efforts to produce any young of it were in vain. |
| D．It used to play an important role in the survival of dinosaurs. |
| A．Weakened. | B．Declined. | C．Multiplied. | D．Rocketed. |
| A．Indifferent. | B．Appreciative. | C．Sympathetic. | D．Tolerant. |
| A．The World’s Loneliest Plant | B．The Last Cycad on Earth |
| C．The Plant That Outlived Dinosaurs | D．The Ancient Cycad found by John Wood |
4 . “How many of us as children have stared up at a church-like top of a giant tree and climbed it in wonder, which is a rally special part of our lives?” asks Bill Laurance, a tropical ecologist at James Cook University. “The leaves of big trees in forests are spreading out in all directions. We’re faced with organisms that have evolved for long periods of ecological stability.”
“There’s a lot to discuss on the issue,” says David Lindenmayer, a conservation ecologist at the Australian National University. “Climate change will mean that, in some forests, big trees won’t reach the same sizes they used to.” The effects of climate change, including long droughts, more invasive species and so on increase the simple physical challenges that big trees face in pulling water from their roots to their leaves and withstanding windstorms.
Lindenmayer and Laurance define “large, old trees” as the largest five percent mature trees within a species. The flexible definition means that in some forests, the large, old trees might be only 20 meters tall and 100 years old.
These large, old trees control the surrounding plant communities, affect water and nutrient distribution, and provide food and shelter for wildlife. “They’re really the breadbaskets of the forest,” says Laurance. “This is a very environmentally and ecologically important group of organisms, and they need special care and handling.” Determining the distribution and habitat requirements for large, old trees in the landscape is the first step towards ensuring their survival, “We have to ensure that what we’re thinking is long-term, to match the way these trees have existed for hundreds or even thousands of years,” says Laurance. “It’s going to be a real challenge to keep some places where there is still wildlife and the big church-like trees that we all really care about.”
1. How does the author lead in the topic of the text?| A．By definition. | B．By comparison. |
| C．By quoting someone’s words. | D．By drawing some conclusions. |
| A．They are affected by various factors. |
| B．They have become shorter but thicker. |
| C．They easily pull water from their roots. |
| D．They grow taller because of climate change. |
| A．The plants around control trees’ survival. |
| B．It is necessary to take good care of big trees. |
| C．Big trees mainly depend on wildlife for survival. |
| D．Planting big trees is the first step in forest protection. |
| A．Protect Forest Giants |
| B．Keep Ecological Stability |
| C．Deal with Forest Organisms |
| D．Fight Against Climate Change |
