Root is the general name of all roots of a plant.There are two types of roots,TaprootandFibrous root systemPoints.Taproot systemtaprootDeveloped and obvious, it is easy to distinguish from lateral roots. The root system composed of this main root and its various levels of lateral roots is called taproot.
When the seed germinates, it first breaks through the seed coat and grows outward, and the part that grows vertically downward is the taproot.As you are familiar withBroad beanWhen it germinates, the root that breaks through the seed coat and stretches out in a white strip is the root, and then it grows downward to form the main root.Similarly, it is used as vegetableYellow bean sprouts、mungbean sproutThey all have a long white thing, which is also the root, and later forms the main root.
lateral root
When the main root grows to a certain length, it will produce some branches, which are collectively called lateral roots.In soybean sprouts and mung bean sprouts, sometimes when the main root grows longer, there will be some lateral branches near the end of the main root, which are called lateral roots.During the growth of lateral roots, they may branch again to form new lateral roots, which are called secondary lateral roots.Of course, there can also be the third level, the fourth level... There is no research on the endless generation of new lateral roots, but as the main root, there is always only one, and there is no second level of main root, which can be said to be non main root.
Adventitious root
Indefinite root isplant growth In the process, the root grows from the stem or leaf, which does not come from the main root or lateral root.For example, after cutting a weeping willow branch and inserting it into the wet soil, a root soon grew on the stem inserted into the mud, which is called adventitious root.A narcissus head, placed in the water for a few days, densely grows a ring root at its bottom, which is also an adventitious root.Adventitious roots can produce branches, such asWeeping willowIts adventitious roots have branches, which are also called lateral roots;Adventitious roots also have unbranched ones, such as narcissusAdventitious rootNo branches.
Distribution characteristics
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The root system of fruit trees is divided into 2~3 layers in the soil, and the upper layerRoot groupThe angle (the angle between the main root and the lateral root) is large, with strong branching, and is easily affected by the ground surfaceenvironment conditionAnd fertilizer and water;The root group angle of the lower layer is small, and its branching is weak, which is less affected by the surface environment and fertilizer and water conditions.
According to the distribution and growth mode of root system in soil, it can be divided into horizontal root and vertical root.The root system that grows nearly parallel to the ground is called horizontal root, and the root system that grows nearly perpendicular to the ground is called vertical root.
Root classification
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root system
The total of plant roots is called root system（root system)，Divided intoTaproot(taproot system)andFibrous root system(fibrous root system)。
Taproot
The root system of a plant consists of an obvious taproot (radicleAnd all levels of lateral roots.grossDicotyledonAll have straight roots, such asUpland cotton(Gossypium hiasutumL.）, soybean (Glycine max（L.)Merr.）Etc.mostlyQiao Lin, shrubs and someherb, for examplecedar、pomegranate、Broad bean、Dandelion、beet, HuradishThe roots of radish and other plants are straight rootsThe characteristic of taproot is that the main root is obvious, and the lateral root grows from the main root, with distinct primary and secondary.From the appearance, the taproot develops vigorouslyCoarsenessIt is easily distinguished from lateral roots in terms of length.By cuttingBattenetc.Vegetative reproductionThe root system of a tree grown fromAdventitious rootAlthough there is no real taproot, one or two of the adventitious roots are often thick, similar in appearance to the taproot, and have the form of taproot, which is also traditionally regarded as taproot.
Fibrous root system
The fibrous roots of plants are composed of manyAdventitious root(byHypocotylAnd the lower boundary produced by the root).The main root cannot be clearly distinguished from the root system (this is becauseradicleIt is caused by stopping growth or slow growth after forming the main root for a period of time).grossMonocotyledonAll are fibrous roots.assorghum(Sorghum vulgarePers.)、Cyperus rotundus(Cyperus rotundusL.), etc.GramineaeFor example, the roots of rice, wheat, various weeds, alfalfa, onion, garlic, lily, corn, narcissus, etc. are fibrous roots.The characteristics of fibrous root system areseed germination The main root degenerates very early, and clusters of whisker like roots grow from the stem base. These roots are not from the old root, but from the base of the stem. They are later generated, called adventitious roots.The number of adventitious roots is amazing, such as a mature plantRyegrassThere are 15 million roots and root branches with a total length of 644kmSurface areaThere is a large volleyball court and 0.57 cubic meters of soil.[2]
