 In this video, we are going to learn about the Anatomy of Roots of Angiosperms. Anatomy is the study of internal structures like cells, tissues and organs and how they are arranged within an organism. As we know, there are two types of roots, tap roots and fibrous roots. Tap roots are seen in dicot plants like sunflowers whereas fibrous roots are seen in monocot plants like grass. Roots function to absorb water and nutrients from the soil. They anchor a plant in one place, store food and also produce some plant growth regulators. Roots have vascular bundles of xylem and phloem arranged in alternating radii in a radial manner. You have phloem towards the periphery and xylem towards the center and they are arranged in an alternating manner. Phloem xylem, phloem xylem. This arrangement is called radial arrangement. To take a look at the internal structure or the anatomy of the root, we need to cut the root horizontally to get the transverse section. Here is how a transverse section of a dicot root looks like. The outermost layer is called epidermis or epilema. Now this is a single layered structure made up of paranchymata cells. The cells of this layer protrude as unicellular projections called root hair. Root hair increase the surface area of water absorption. Roots do not have a waxy coating called cuticle that is found in stems. Can you think of a reason why cuticle is absent in roots? Below the epidermis is the multi-layered cortex. So cortex is made up of paranchymata cells which are circular in shape and have plenty of intercellular space between them. Cortex exists to offer structural support and transports nutrients to the root. The innermost layer of the cortex is called endodermis, endo meaning inside. So endodermis is made up of barrel-shaped cells arranged with no intercellular space. The radial walls of the endodermis which means the walls that run from the inside to the outside of the cell and the tangential walls which are the walls that run along the circumference of the cell are covered with waxy subarin deposited in the form of casperian strips. Now these strips are impermeable to water and they restrict the flow of water and ions within the cell. The layer of cells below the endodermis is called the pericycle. So the pericycle is involved in the secondary growth of the root. In secondary growth the width of the root increases by the formation of vascular cambium and the cells of the pericycle are involved in the initiation of vascular cambium. Remember that dicot roots have a primary root from which several lateral roots grow. So the growth of lateral roots is also from the cells of the pericycle. The vascular bundles in the roots are located within the endodermis. Xylem and phloem are arranged in an alternating manner in a radial way. So this is xylem here and this is phloem here. So xylem phloem. So in xylem proto xylem is located towards the periphery and the metazylem is located towards the centre. Proto xylem forms first during primary growth and afterwards metazylem forms. Phloem lies below the pericycle cells in between two patches of xylem and the tissue between xylem and phloem is called conjunctive tissue. Dicot roots have around two to four vascular bundles. So in this image you can see four vascular bundles, four xylem patches and in between them there are four phloem patches. In dicot roots the pith is located in the centre but it's quite small and underdeveloped but it is made up of parainchymata cells and functions to store nutrients. So all of the cells below the endodermis, the pith, the pericycle and the vascular bundles are collectively called the steely. Monocot root is very similar to dicot root and this is a transverse section of a monocot root. In many ways it is very similar to the dicot root. It also has a single layer of epidermis from which root has a projected. It has several layers of cortex cells which have intercellular spaces. The innermost layer is called the endodermis and below that is the pericycle. But there are a few differences between a monocot root and a dicot root. Monocot roots do not undergo secondary growth. So the cells of the pericycle are not involved in the secondary growth in monocots. Monocots have more than six vascular bundles. As you can see in this image there are one, two, three, four, five, six, seven, eight. Around six to eight patches of vascular bundles are seen in monocot roots. So these are eight xylem patches and in between them are eight phloem patches. The number is higher compared to dicot roots which have only around two to four vascular bundles. But in the case of monocot roots as well, the vascular bundles are arranged in a radial alternating manner. The pith in monocot roots is large and well developed. It stores water and nutrients in monocot roots as well but it is quite large and well developed. So there you have it, the different parts of the root and their functions.