Summer 2016 CBT110

The Roots Root is the organ of the plant, originates from the radicle of the embryo. The first root that comes from a plant is called the radicle. It grows downwards, fixes the seedling later the plant to the ground and absorbs raw food materials the soil.

Characteristics of roots Root does not normally bear buds. Root end is protected by a cup or thimble known as root cap. Root bears unicellular hairs, while the stem bears mostly multicellular hairs. Nodes and internodes are absent in roots.

Functions of Roots Anchorage: Root anchors the plant to the soil and provides mechanical support to the plant. The root system firmly anchors the plant to the soil keeps the plant upright. Absorption: The major physiological function is absorption of water and nutrients from the soil. Conduction: The root is concerned with the conduction of water and mineral salt, sending them upwardly into the stem and ultimately to the leaf. Storage: Roots can store food materials like sweet potato. Photosynthesis: Some plants develop chlorenchymatous tissue in root and thus carry out photosynthesis and called photosynthetic roots, uncommon function of root.

Parts of Roots

Types of Roots Tap Root: Roots that develops from the radicle, either directly from it or its branches is called normal roots

Adventitious root Roots that grows from any part of the plant body other than the radicle are called adventitious roots.

Modifications of roots Fusiform root: Swollen in the middle and gradually tapering both ends. e.g. radish

Napiform root: The upper part becomes almost spherical and sharply tapering at the bottom part. e.g. turnip.

Conical root When the root is broad at the base and it gradually tapper towards the apex like a cone, it is said to be conical. e.g. Carrot.

Modified Adventitious Roots Fasciculated root: When several tubercular roots occur in a cluster or fascicle at the base of the stem are said to be fasciculate as in Dahlia and Asparagus

Moniliform root: When there are some swellings in root at frequent intervals, it is said to be moniliform root. e.g. Teasel gourd

Tuberous root When the root is thick and fleshy but does not maintain any particular shape, it is said to tuberous or tubercular. e.g. sweet potato.

Specialized Roots Epiphytic root: There are certain plants, commonly orchids, which grow on branches of trees. Such plants are known as epiphytes.

Nodal roots adventitious roots that form characteristically in rings from stem tissues around a node.

Prop or stilt roots adventitious roots that develop on a trunk or lower branch that begin as aerial roots

Aerating roots (knee root or knee or pneumatophores Spongy, aerial roots of marsh or swamps, such as in mangroves, where roots are present in waterlogged soils and cannot obtain enough oxygen for maintaining healthy tissues.