英语_阅读_Plant's defenses

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Animals can move from place to place, but plants cannot. When an animal is under attack, it can run away or **fight back**. Plants certainly cannot run away, and they have no teeth or claws. But plants can protect themselves by using both physical and chemical means.

Some plants have their own ways to keep animals **away**. For example, the leaves of the holly plant have sharp points that discourage grass-eating animals. Holly leaves on lower branches have more sharp points than leaves on upper branches. This is because the lower leaves are **easier** for most animals to reach.

Some plants, such as the oak tree, have special ways to discourage leaf-eating animals. They have thick and hard leaves that are **difficult** for animals to eat. Some grasses may contain a sandy material; eating such grasses wears down the animal’s teeth.

Many plants also have chemical defenses. Some plants produce chemicals that taste bitter or cause an unpleasant reaction. Some plants may fight against an **attack** by increasing the production of these chemicals. When an insect bites a tobacco leaf, the leaf produces a chemical messenger. This messenger sends to the roots the information to produce more nicotine. The higher levels of nicotine discourage the insect.

Many plants **rely on** both physical and chemical defenses. A certain plant in China, for example, has sharp leaves, and each sharp leaf contains poisonous venom. A single experience with this kind of plant will teach an animal not to eat the leaves of it in the future.

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Animals can move from place to place, but plants cannot.
动物可以在不同的地方之间移动，但植物不能。

When an animal is under attack, it can run away or fight back.
当动物受到攻击时，它可以逃跑或反击。

Plants certainly cannot run away, and they have no teeth or claws.
植物当然无法逃跑，而且它们没有牙齿或爪子。

But plants can protect themselves by using both physical and chemical means.
但是，植物可以通过物理和化学手段来保护自己。

Some plants have their own ways to keep animals away.
有些植物有自己独特的方式来让动物远离。

For example, the leaves of the holly plant have sharp points that discourage grass-eating animals.
例如，冬青植物的叶子上有尖锐的刺，能阻止食草动物。

Holly leaves on lower branches have more sharp points than leaves on upper branches.
冬青树下部的叶子比上部的叶子有更多的尖刺。

This is because the lower leaves are easier for most animals to reach.
这是因为下部的叶子对于大多数动物来说更容易接触到。

Some plants, such as the oak tree, have special ways to discourage leaf-eating animals.
有些植物，如橡树，有特殊的方式来阻止食叶动物。

They have thick and hard leaves that are difficult for animals to eat.
它们有厚实坚硬的叶子，这些叶子让动物很难以食用。

Some grasses may contain a sandy material; eating such grasses wears down the animal’s teeth.
有些草类植物可能含有沙质物质；食用这些草会磨损动物的牙齿。

Many plants also have chemical defenses.
许多植物也有化学防御机制。

Some plants produce chemicals that taste bitter or cause an unpleasant reaction.
有些植物会产生苦味的化学物质，或引起不愉快的反应。

Some plants may fight against an attack by increasing the production of these chemicals.
一些植物通过增加这些化学物质的生产来应对攻击。

When an insect bites a tobacco leaf, the leaf produces a chemical messenger.
当昆虫咬住烟草叶时，叶子会产生一种化学信使。

This messenger sends to the roots the information to produce more nicotine.
这个信使将信息传递给根部，促使根部产生更多的尼古丁。

The higher levels of nicotine discourage the insect.
尼古丁的较高浓度会阻止昆虫。

Many plants rely on both physical and chemical defenses.
许多植物依赖物理和化学防御来保护自己。

A certain plant in China, for example, has sharp leaves, and each sharp leaf contains poisonous venom.
例如，中国某种植物的叶子很尖锐，每片尖叶中都含有毒液。

A single experience with this kind of plant will teach an animal not to eat the leaves of it in the future.
动物与这种植物的单次接触就会教会它以后不再食用这种植物的叶子。