How do plants talk to each other?
Read How do plants talk to each other? and check the IELTS Reading answers. In 1983, plant scientists Jack Schultz and Ian Baldwin reported that the leaves of young maple trees increased their defense systems when exposed to maples that had been damaged by plant-eating (herbivorous) insects. The in…
Passage preview
In 1983, plant scientists Jack Schultz and Ian Baldwin reported that the leaves of young maple trees increased their defense systems when exposed to maples that had been damaged by plant-eating (herbivorous) insects. The injured trees, they suggested, were alerting neighbors to the presence of a predator by releasing chemical signals into the air. But the plant research community did not accept this. The results were difficult to replicate, critics pointed out. Many also questioned how it could be evolutionarily stable if it benefited neighboring plants but not the plant releasing the signal. By the late 1980s, most ecologists felt that Schultz and Baldwin’s idea had been discredited.
Vocabulary from this passage
11 words worth learning before you sit the test, each with the sentence it appears in.
- acoustic adjective
Relating to sound or the sense of hearing; characterized by the production or transmission of sound
Researchers suspect that plants might use an acoustic channel of communication to alert their neighbors to threats.
- botanical interaction noun
The complex ways in which different plant species communicate, compete, or cooperate within an ecosystem
Scientists are uncovering a new realm of botanical interaction where plants exchange information without a nervous system.
- close proximity noun
Nearness in space, time, or relationship; the state of being physically close to something else
Tobacco plants became resistant to herbivores when grown in close proximity to damaged sagebrush plants.
- discredited verb
Loss of reputation or respect; having been shown to be false or not worthy of belief
By the late 1980s, the initial idea of plant communication had been largely discredited by ecologists.
- herbivorous adjective
An animal or organism that feeds primarily or exclusively on plants or plant-based matter
Maple trees increased their defenses when exposed to trees damaged by herbivorous insects like aphids.
- inhibit verb
To hinder, restrain, or prevent an action or process from occurring or developing normally
Fennel plants are known to release chemicals that inhibit the growth of other competing plant species.
- kin selection noun
Natural selection in favor of behavior by individuals that may decrease their chance of survival but increases that of their relatives
VOC-based signaling may have evolved through kin selection by aiding related plants of the same species.
- microscopic pores noun
Extremely small openings on the surface of leaves that regulate the exchange of gases and water
Stressed garden pea plants responded to drought conditions by closing their microscopic pores to conserve water.
- physiological response noun
An automatic reaction that triggers a physical change in the body of a living organism
Plants use internal signals to coordinate physiological responses that protect individual sections from environmental stress.
- sensory mechanisms noun
Biological systems or structures that allow an organism to perceive and respond to external stimuli
Taking advantage of acoustic signals would require sensory mechanisms in plants that have not yet been described.
- volatile organic compounds noun
Organic chemicals that have a high vapor pressure at ordinary room temperature, often used in signaling
Sagebrush plants release volatile organic compounds to induce defense responses in their nearby plant neighbors.
Answers with explanations
- 14. iii
Paragraph A discusses how the scientific community initially refused to accept Schultz and Baldwin's findings. The paragraph culminates by stating that most ecologists felt the idea had been **discredited** (rejected). This matches heading iii: 'The widespread **rejection of an idea**'.
- 15. vi
Paragraph B explains how later experiments began providing **convincing indications** that the initially discredited theory was actually correct. This directly maps to heading vi: '**Evidence leading to renewed belief** in a theory'.
- 16. viii
Paragraph C attempts to answer why a plant would waste resources sending signals. It outlines theories for how the **sender benefits**, specifically by enhancing its 'extended fitness' through kin selection. This connects to heading viii: 'A suggested **benefit to the sender** of plant communication'.
- 17. i
Paragraph D focuses on communication happening beneath the soil. It discusses signals being passed through **plant roots** and networks of **fungi**. This directly correlates with heading i: 'Sending messages **underground**'.
- 18. iv
Paragraph E presents an experiment by Gagliano where chili plants **developed more quickly** when placed next to a different species (fennel). This demonstrates one plant increasing the growth rate of another, matching heading iv: 'One species **accelerating growth** in another'.
- 19. ii
Paragraph F discusses the future applications of plant communication research, specifically how it could be applied to **agriculture** to cultivate hardier crops. This clearly outlines heading ii: 'Potential **advantages for farmers**'.
- 20. roots
The blank requires a noun identifying the medium through which Novoplansky claims plants send messages. The text explicitly states that 'distress signals can be passed through the plants' **roots**'. Thus, 'roots' is the correct answer.
- 21. drought
The blank requires a noun describing the specific environmental conditions created around the first plant. The passage states Novoplansky's team subjected the plants to 'conditions similar to those experienced in a **drought**'. Therefore, 'drought' is grammatically and factually correct.
- 22. fungi
The blank requires a plural noun defining the underground networks connecting plants. The passage mentions Johnson's research into 'the labyrinths of hair-like **fungi**'. This perfectly fits the description of subterranean networks extracting resources.
- 23. aphids
The blank requires a noun naming the specific plant-eating insects used in the experiment. The text states that the plants were 'infested with **aphids** – small herbivorous insects'. 'Aphids' precisely fits the context.
- 24. C
The question asks who believes plant communication research will help our food supply (agriculture). The text quotes **David Johnson** discussing the application of this knowledge to **agriculture**, stating it is 'definitely on the horizon'. Therefore, Researcher C is the correct match.
- 25. A
The question links to the idea that communication evolved from internal self-help mechanisms. In Paragraph C, the hypothesis of signals coordinating 'its own physiological responses to protect itself' is supported by **Richard Karban**, who states plants might be 'co-opting that process'. This corresponds to Researcher A.
- 26. B
The question identifies a researcher noting a massive shift in attitudes toward plant communication over recent decades. The quote contrasting the 'very weird' perceptions in the late 1980s with 'today, there is no doubt' belongs directly to **Ariel Novoplansky**. This links to Researcher B.