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  • 根根

    Close-up view of complex tree roots spreading across the ground.

    Now those are some serious roots. But what exactly are roots?
    ::现在,这些是一些严肃的根。但到底什么是根?

    There are taproots and fibrous roots , primary roots and secondary roots . And they always seem to know which way to grow. Roots are very special plant organs . How and why?
    ::树根和植物根、原始根和次要根。他们似乎总是知道种植的方法。根是非常特殊的植物器官。怎么和为什么?

    Roots
    ::根根

    Plants have specialized organs that help them survive and reproduce in a great diversity of habitats . Major organs of most plants include roots, , and leaves.
    ::大多数植物的主要器官包括根部、叶部和叶部。

    Roots are important organs in all . Most vascular plants have two types of roots: primary roots that grow downward and secondary roots that branch out to the side. Together, all the roots of a plant make up a root system .
    ::根是所有器官的重要器官。大多数血管植物有两种根根:一种是向下生长的根根,另一种是向外延伸的第二根根根。 植物的所有根合在一起组成根系统。

    Root Systems
    ::根系统

    There are two basic types of root systems in plants: taproot systems and fibrous root systems. Both are illustrated in Figure .
    ::植物中根系系统有两种基本类型:根根系统和纤维根系统。

    • Taproot systems feature a single, thick primary root, called the taproot , with smaller secondary roots growing out from the sides. The taproot may penetrate as many as 60 meters (almost 200 feet) below the ground surface. It can plumb very deep sources and store a lot of food to help the plant survive drought and other environmental extremes. The taproot also anchors the plant very securely in the ground.
      ::塔普根系统有单一的、厚厚的原始根,称为水管根,小的第二根根从两侧长出来。 水管根可能渗透到地表下60米(近200英尺)的地表以下。 它可以释放非常深的源头并储存大量食物以帮助植物生存干旱和其他极端环境。 水管根也非常安全地固定在地面上。
    • Fibrous root systems have many small branching roots, called fibrous roots , but no large primary root. The huge number of threadlike roots increases the surface area for absorption of water and minerals , but fibrous roots anchor the plant less securely.
      ::纤维根系统有许多小根根根,叫做纤维根,但没有大根根根。 大量线索根增加了吸收水和矿物的地表面积,但纤维根却不那么安全地固定了植物。

    Comparison of taproot and fibrous root systems in plants, highlighting their structures.

    Dandelions have taproot systems; grasses have fibrous root systems.
    ::沙漠有根茎系统;草有纤维根系统。

    Root Structures and Functions
    ::根结构和函数

    As shown in Figure , the tip of a root is called the root cap . It consists of specialized that help regulate primary growth of the root at the tip. Above the root cap is primary meristem , where growth in length occurs.
    ::如图所示,根尖被称为根盖。它由有助于调节根尖初级增长的专门技术组成。根盖之上是主要的中间线,其长度会增长。

    Root structure with labels for epidermis, root hairs, meristems, and vascular tissues.

    A root is a complex organ consisting of several types of tissue. What is the function of each tissue type?
    ::根是一个由几种组织组成的复杂器官。 每个组织类型的功能是什么?

    Above the meristem , the rest of the root is covered with a single layer of epidermal cells. These cells may have root hairs that increase the surface area for the absorption of water and minerals from the soil . Beneath the epidermis is , which may be filled with stored starch . Bundles of form the center of the root. Waxy layers waterproof the vascular tissues so they don’t leak, making them more efficient at carrying fluids. Secondary meristem is located within and around the vascular tissues. This is where growth in thickness occurs.
    ::根部的其余部分被单层的上皮细胞覆盖。 这些细胞可能有根毛, 增加表层面积, 从土壤中吸收水和矿物质。 在上皮下, 可能被储存的星座填满。 形状捆绑在根中央 。 轴层防水, 防止血管组织泄漏, 使其更高效地携带液体 。 二次内皮位于血管组织内部和周围 。 这是厚度增长的地方 。

    The structure of roots helps them perform their primary functions. What do roots do? They have three major jobs: absorbing water and minerals, anchoring and supporting the plant, and storing food.
    ::根的结构有助于他们履行其首要功能。根是做什么的?他们有三大工作:吸收水和矿物质,固定和支撑工厂,以及储存食物。

    1. Absorbing water and minerals: Thin-walled epidermal cells and root hairs are well suited to absorb water and dissolved minerals from the soil. The roots of many plants also have a mycorrhizal relationship with for greater absorption.
      ::吸收水和矿物:薄壁上皮细胞和根毛非常适合从土壤中吸收水和溶解矿物,许多植物的根部也与增加吸收有细微关系。
    2. Anchoring and supporting the plant: Root systems help anchor plants to the ground, allowing plants to grow tall without toppling over. A tough covering may replace the epidermis in older roots, making them ropelike and even stronger. As shown in Figure , some roots have unusual specializations for anchoring plants.
      ::固定和支持植物:根系统帮助将植物固定在地上,使植物在不翻倒的情况下长高。 坚硬的覆盖可能取代老根部的皮层,使其变得绳索般,甚至更强大。 如图所示,有些根有不同寻常的固定植物专门技术。
    3. Storing food: In many plants, ground tissues in roots store food produced by the leaves during . The bloodroot shown in Figure stores food in its roots over the winter.
      ::储存食物:在许多植物中,根部的地面组织储存着叶子在冬季产生的食物。图中显示的血根储存着食物在冬季的根部。

    Comparison of mangrove roots with stilts for elevation and bloodroot plant storing food.

    Mangrove roots are like stilts, allowing mangrove trees to rise high above the water. The trunk and leaves are above water even at high tide. A bloodroot plant uses food stored over the winter to grow flowers in the early spring.
    ::红树根像尖塔,让红树高到水的上面。 树干和树叶甚至高涨时也高于水。 血根植物利用冬季储存的食物在春初种植花朵。

    Root Growth
    ::根增长

    Roots have primary and secondary meristems for growth in length and width. As roots grow longer, they always grow down into the ground. Even if you turn a plant upside down, its roots will try to grow downward. How do roots “know” which way to grow? How can they tell down from up? Specialized cells in root caps are able to detect gravity. The cells direct meristem in the tips of roots to grow downward toward the center of Earth. This is generally adaptive for land plants. Can you explain why?
    ::根有长长长和宽宽长增长的初级和二级中间线。 随着根长, 它们总是会长到地面上。 即使将植物翻倒, 其根会试图向下增长。 根会如何“ 知道” 成长的方式? 它们如何从上到下分辨? 根盖中的专门细胞能够检测引力 。 细胞引导根尖中的细胞向下向下向向地球中心生长。 这通常对陆地植物有适应性 。 你能解释为什么吗 ?

    As roots grow thicker, they can’t absorb water and minerals as well. However, they may be even better at transporting fluids, anchoring the plant, and storing food (see Figure ).
    ::随着根长得更厚,它们也吸收不了水和矿物质。 然而,它们可能更擅长运输液体、固定工厂和储存食物(见图 ) 。

    A hand holding harvested sweet potatoes with green vines around them.

    Secondary growth of sweet potato roots provides more space to store food. Roots store sugar from photosynthesis as starch. What other starchy roots do people eat?
    ::甘薯根的二次生长为储存食物提供了更多空间。 根将光合作用糖作为淀粉储存。 人们还吃什么其他星系根呢?

       

     

     

    Science Friday : Plants in Space!
    ::科学星期五:太空植物!

    For humans to travel to the Moon and Mars, astronauts will need to understand how to grow plants in extreme climates in order to help them stay alive. In this video by Science Friday , Dr. Anna-Lisa Paul and Dr. Robert J. Ferl send weeds to space to study their behavior on a molecular level.
    ::为了让人类前往月球和火星,宇航员需要了解如何在极端气候条件下种植植物,以帮助他们生存。 在科学周五的这段视频中,安娜-莉萨·保罗博士和罗伯特·费尔博士将杂草送去太空研究分子层面的行为。

     

     

    Summary
    ::摘要

    • Roots absorb water and minerals and transport them to stems. They also anchor and support a plant, and store food.
      ::根吸收水和矿物质,并将它们输送到水中,它们也固定和支撑一个工厂,储存食物。
    • A root system consists of primary and secondary roots.
      ::根系统由初级和二级根组成。
    • Each root is made of dermal, ground, and vascular tissues.
      ::每个根都是由皮肤、地面和血管组织组成的。
    • Roots grow in length and width from primary and secondary meristem.
      ::根长宽长的长长长 从初级和二级的中间。

    Review
    ::回顾

    1. What are root hairs? What is their role?
      ::什么是根毛?他们的角色是什么?
    2. Identify three major functions of roots.
      ::查明根的三个主要功能。
    3. Contrast a taproot system with a fibrous root system.
      ::和根根系统比对
    4. Explain how roots “know” which way to grow.
      ::解释如何根“知道”成长的方式。