| A．From not enough water. |
| B．From not enough sun. |
| C．From not enough plant food. |
2 . It’s breathtaking to watch the delicate spring wildflowers come out from their blanket of leaves, bloom, develop and disperse (传播) fruit, all in a matter of a few short days or weeks.
Although they look fragile, these are tough little plants, each focusing its efforts on spreading its species. They have evolved to have a wide range of flower structures and colors, some with fragrances, attracting many different insect species to assist them in pollination (授粉).
There is one strategy (策略) that a surprising number of spring blooming native plants have evolved in common: seed dispersal by ants. As many as thirty percent of the spring flowering plant species in the forests of eastern North America have evolved to take advantage of this situation to benefit themselves. These species have evolved to provide food attached to their seeds to encourage ants to disperse those seeds. This food, called an elaiosome, is a specialized fat body whose chemical composition more closely matches that of the insects that ants prefer than it does that of a seed.
When a fruit opens to disperse its seeds, the elaiosomes are an instant attraction for ants. They take the seed with its attached elaiosome back to their nests for consumption there, but they just eat the elaiosome, their preferred food, and dispose of the seed on their trash pile. This tends to be an environment that is rich in nutrients, and will benefit the growth of the new plant. Just to make sure the ants don’t eat the seeds in addition to the elaiosome, some plant species have hard seed coatings that ants can’t really bite through.
This evolutionary adaptation is somewhat similar to the strategy of plants that have evolved to surround their seeds with fleshy fruits to attract birds to assist them with seed dispersal. Given the fact that there are fewer birds available in early spring to help with seed dispersal, it makes sense that the early blooming plants evolved to partner instead with the ants for this service.
Did you ever wonder how your Spring Beauty managed to pop up in new locations in your lawn or garden? Thank an ant!
1. How many methods do wildflowers have to attract animals according to the text?| A．Two. | B．Three. | C．Four. | D．Five. |
| A．It’s hard to digest. | B．It’s impossible for ants to resist. |
| C．It makes the earth rich in nutrients. | D．It’s often thrown into the trash pile. |
| A．Ants are creative and hardworking. |
| B．Ants are better at dispersing than birds. |
| C．The birds in the early year are not enough. |
| D．The birds are not interested in their fleshy fruits. |
| A．Thank Ants for Wildflowers |
| B．Wildflowers Discover Their Treasures |
| C．New Species of Wildflowers are Found |
| D．Ants Are Superheroes Protecting Environment |
1. Why is the baobab tree thought to be strange-looking?
| A．Its trunk sometimes measures more than ten metres in diameter. |
| B．Its trunk is thicker at the top than at the bottom. |
| C．Its branches near the top are longer than those near the ground. |
| A．Its leaves. | B．Its trunk. | C．Its skin of the tree. |
| A．Its empty trunk can be used by people to build everything. |
| B．Its flowers can turn into a kind of cucumber. |
| C．Its leaves and branches can keep the rain water cool and clean. |
| A．The baobab—unusual but useful. |
| B．The baobab—a tree that people can make good use of. |
| C．The baobab—a strange tree that can make ropes. |
| A．Bring flowers. | B．Take a pot plant. |
| C．Buy postcards. | D．Send fruits. |
5 . Sunflowers have increasingly become popular on social media. People enjoy the bright yellow flowers and take pictures of themselves in bright fields of sunflowers, which are called “sunflower selfies.”
Actually, it is easy to grow your own sunflowers. Here are some instructions.
Do you want to start growing sunflowers from seeds?
Then, plant each seed into soil apart. Keep the soil wet, but not too wet, until the seeds begin to grow. During the growth process, you should water regularly the plants. When they grow up, it is best to put up some shelves to protect the plants from strong winds.
When seeds will start coming out of the head, it is time for harvest. Cut the flowers off and put them into a bag or container. In this way, the seeds will not fall out. Then remove the seeds by rubbing flowers with your hands or a hard brush over a container.
Finally, you’d better select those full seeds for food.
| A．Equally attractive is the delicious taste. |
| B．Sunflower seeds may be eaten cooked or uncooked. |
| C．You can also tie the plants to something tall for support. |
| D．Some kinds of sunflowers can grow up to three meters tall. |
| E．It is important to loosen the soil before the seeds are planted. |
| F．Put the selected seeds in room-temperature water for 2-8 hours. |
| G．They will develop long roots that work their way deep into the ground. |
1. Why must trees be planted according to the talk?
| A．To improve farms. | B．To replace desert. | C．To fight climate change. |
| A．4%. | B．13%. | C．17%. |
| A．Farmers’. | B．Scientists’. | C．Business experts’. |
1. What makes potted roses easier to plant?
| A．Lower nutrition requirement. |
| B．Stronger cold resistance. |
| C．Better root development. |
| A．They need less soil. |
| B．They are easier to transport. |
| C．Their planting time is fixed. |
| A．Damp condition. | B．Heavy sunshine. | C．Continuous watering. |
| A．Types of roses. | B．Ways of rose packing. | C．Tips on rose growing. |
8 . Most plants you see out in nature are leafy and green, at least for some part of their lives. That’s because they use green pigments, which are called chlorophyll (叶绿素), to harvest energy from sunlight. But the plant Hydnora Africana, doesn’t have leaves or chlorophyll at all.
So, how can it survive? Well, it’s a parasite (寄生), and H Africana attaches itself to other plants’ roots, and begins getting sugars, minerals, and water from its host.
At the same time, the parasite grows a root system, living completely underground, until it’s ready to reproduce. At which point, it grows one of the strangest looking flowers in the world. When the flower’s mature, it breaks the soil from beneath and reaches out in order to be pollinated (授粉).
But just as this plant doesn’t look like the normal flower, it doesn’t smell like one either. It gives out a smell like a rotting (腐烂) animal . The smell attracts insects and flies looking for a delicious meal. But when they get inside the flower and find no tasty treat, they can’t get back out again.
There’s a sort of room inside the flower, and the top of the room closes behind the insects. The walls of the flower are also slippery, making escape even more difficult.
Over the course of about a day, the flower’s male organs mature, and the insects get coated in pollen. And at the end of this transformation, the inside of the plant gets less slippery, and the chamber opens, allowing the insects and flies to escape.
At that point, attracted by a new rotting smell, they might just find another H Africana flower and pollinate it as they fall inside.
1. Why is chlorophyll so important to plants?| A．Chlorophyll gives plants green color. |
| B．Chlorophyll helps leaves to grow. |
| C．Chlorophyll can harvest energy from sunlight. |
| D．Plants cannot survive without Chlorophyll . |
| A．It’s a parasite without roots. |
| B．It gets food through other plants’ root. |
| C．It never grows out of the ground. |
| D．Its flowers smell sweet. |
| A．find tasty treat inside the flower. |
| B．never get out of the flower again. |
| C．get little chance to pollinate successfully. |
| D．escape after being trapped about a day. |
| A．What is a parasite. |
| B．How a parasite to survive. |
| C．How H Africana reproduce. |
| D．Why bad smell is so useful. |
9 . Hawk Salvage, located in the historic neighborhood on Grand Avenue, is the place to find one-of-a-kind things. The store features a collection of curious things of the past and, most recently, a huge selection of rare and unique houseplants.
Founded by Greg Hawk, who has traveled from coast to coast finding items for his store, Hawk Salvage is like a well-kept history museum, its walls and display cases were filled with ancient art and historical photos. Even the space is a slice of history — it served as an automotive garage in the1940s. The front of the shop is home to lots of greenery.
On October 17 from 10 a.m. to 4 p.m., the store will host its first-ever community plant swap, where plant parents can bring their plants and trade them for new plants. Visitors can learn tips and tricks from other fellow plant lovers and enjoy live music, artist demonstrations, food trucks and more. It will be a plant party for the ages, Hawk says. To take part in the plant swap, guests must bring at least one live and healthy plant to trade for another plant of equal size.
Because his regular picking trips was put on hold, Hawk, who is also interested in gardening, started propagating(繁殖)plants. “I started looking at houseplants and it just opened up this huge can of worms of all the cool things that are out there, and now I find myself with more plants than I want to take care of.” he says. Hosting an event where he could clear away some of his plants while reconnecting the community is a win-win situation, he adds.
Hawk says the event is open to everyone. His advice for new plant fans? “Be patient. Buy something simple to start with. Everything dies, so you’re going to kill plants — it’s part of the process,” he says. “I think the biggest tip that I would give is not to be afraid to experiment with your plants.”
1. What can visitors usually do in Hawk Salvage?| A．Trade their plants for others. | B．Get their cars or trucks repaired. |
| C．Buy some rare and unique things. | D．Draw beautiful pictures on its walls. |
| A．Owning a large garden. | B．Bringing some greenery. |
| C．Having planting experience. | D．Being good at hosting plant parties. |
| A．Why Hawk ended his regular picking trips. | B．Why Hawk decided to host the plant swap. |
| C．How Hawk took care of his plants in the past. | D．How Hawk started his journey as a plant-lover. |
| A．They should learn by experience. | B．They should stay away from houseplants. |
| C．They should be careful when planting. | D．They should turn to experienced planters. |
10 . The Mystery of Why Sunflowers Turn to Follow the Sun — Solved
Scientists have answered a burning question central to sunflowers: Why do young flowers always face the sun over the course of a day?
And also: Once sunflowers become full-grown, why do they stop tracking the sun and only face east?
In a newly-published article, researchers claim that a young plant’s sun-tracking (also called heliotropism) can be explained by circadian rhythms — the behavioural changes tied to an internal clock that humans also have, which generally follows a 24-hour cycle.
“Growth rates on the east side were high during the day and very low at night, whereas growth rates on the west side were low during the day and higher at night,” the journal article says.
The researchers tied plants up so they couldn’t move or turned them away from the sun — and they found those flowers eventually had “fewer organic materials and less leaf area” than flowers that could move with the sun.
Full-grown sunflowers respond differently to the sun. According to the article, “As overall growth slows down, the circadian clock ensures that the plant reacts more strongly to light early in the morning than in the afternoon or evening, so it gradually stops moving westward during the day.”
The researchers compared full-grown flowers facing east with those they turned to face west, and found that east-facing flowers attracted five times as many helpful pollinators. That’s because the east-facing flowers heat up faster and bees like warm flowers.
“Just like people, plants depend on the daily rhythms of day and night to function,” Anne Sylvester, director of the National Science Foundation’s Plant Genome (基因组). Research Programme said in a press release. “Sunflowers, like solar panels, follow the sun from east to west. These researchers explore information in the sunflower genome to understand how and why sunflowers track the sun.”
UC Berkeley professor and co-author of the study, Benjamin Blackman, believes that the connection between circadian rhythms and growth could be applicable to other researches. “The more general point, that one of the circadian clock’s adaptive functions is to regulate the timing and strength of growth responses to environmental signals, is one that I think will apply to a broad range of qualities and species.” he said.
1. What did the researchers discover when they tied the sunflowers up?________| A．They still tracked and faced towards the sun. |
| B．They grew faster during the daytime than they did at night. |
| C．Their growth rates were lower than those of flowers facing the sun. |
| D．The growth rates on the west side were higher than those on the east. |
| A．Because they will not be affected by light anymore. |
| B．Because they would stop growing up if they faced west. |
| C．Because they are not active at all during afternoons or evenings. |
| D．Because they are more sensitive to light in the early morning from the east. |
| A．Bees. | B．Plants. | C．Energy. | D．Researchers. |
| A．Exploring information in the sunflower genome. |
| B．Comparing human’s circadian rhythms with sunflowers’. |
| C．Comparing full-grown flowers facing east with those facing west. |
| D．Exploring how circadian rhythms affect the growth of other species. |
