Desert plants

Desert plants have adapted to the arid climate by using both physical and behavioral mechanisms. Some plants have developed to take advantage of the seasons when moisture is at a premium and/or when it is coolest. One of this category of plants are ‘annuals’, plants that live for only a season. The term ‘annuals’ implies blooming yearly, but since this is not always the case, desert annuals are more accurately referred to as ‘ephemerals’. Many of them can complete an entire life cycle in a matter of months, some in just weeks.

Desert plants must act quickly when heat, moisture and light inform them it’s time to bloom. Ephemerals are the sprinters of the plant world, sending flower stalks jetting out in a few days. The peak of this bloom may last for just days or weeks, depending on the weather and difference in elevation. The higher one goes, the later blooms come. Different varieties of plants will be in bloom from day to day, and even hour to hour, since some open early and others later in the day.

Ephemerals such as Desert Sand Verbena, Desert Paintbrush and Mojave Aster usually germinate in the spring following winter rains. They grow quickly, flower and produce seeds before drying and scattering their progeny on the desert floor. These seeds are extremely hardy. They remain dormant, resisting drought and heat, until the following spring – sometimes two or three springs – when they repeat the cycle, germinating after winter rains to bloom again in the spring. There are hundreds of species of ephemerals that thrive in the deserts of the American Southwest, and if you examine the desert ground closely, you will likely find dozens of annual seeds in every handful of soil.

1. Which of the following best describes the main point of the passage?

a) The desert soil is full of drought-resistant annual seeds.

b) Annual winter rainfall allows the ephemerals to bloom.

c) Different plants flower at different times.

d) Ephemerals have adjusted to the weather conditions.

2. It can be inferred from the passage that ephemerals

a) flower more quickly than other plants.

b) need to have high temperatures before they can flower.

c) only bloom at high altitudes.

d) are at their peak when they have flowered for a few days.

3. According to the passage, the seeds of the ephemeral

a) germinate every year.

b) are very sturdy.

c) bloom every spring.

d) do not live long on the desert ground.

4. What do some plants take advantage of?

a) The autumn seasons.

b) The drought each summer.

c) The temperature and humidity.

d) The winter rains and very cold temperatures.

5. According to the passage, the seeds on the desert floor remain

a) there for two or three years in every handful of soil.

b) inactive until conditions are suitable for them to flower.

c) on the desert floor drying out.

d) thriving in the deserts of the American Southwest.

17. You are going to read an article about a famous conservation project. For questions 1-7, choose the answer (A, B, C or D) which you think fits best according to the text. Compare your answers to your partner’s.