BIO1L- Morphology of the Roots PDF

UNIT 3 OBJECTIVES: At the end of the chapter 3, the students shall be able to: 1. Differentiate the types of root systems in plants 2. Identify the external and internal parts of a dicot stem 3. Describe simple and compound leaves  UNIT 3 MORPHOLOGY OF THE...

UNIT 3 OBJECTIVES: At the end of the chapter 3, the students shall be able to: 1. Differentiate the types of root systems in plants 2. Identify the external and internal parts of a dicot stem 3. Describe simple and compound leaves  UNIT 3 MORPHOLOGY OF THE ROOTS Importance of Roots 1. Absorption of Water and Nutrients 2. Anchorage 3. Storage 4. Transport 5. Symbiosis Root The root system is growing at downward- direction.  When a seed germinates, the first structure to emerge is called the radicle. The radicle grows into the primary root or taproot. The primary root develops lateral branches (lateral roots), which can be secondary and tertiary roots. Together, these roots form the entire root system. Structure of the Roots 1.Root Cap - a thimble or cap-like structure that protects the apical meristem (the tip of the root) from damage. It is continuously worn out and replaced as the root grows. In aquatic plants like water hyacinth, the root cap is called a root pocket. 2. Root Tip - where most of the action takes place as it composes of actively dividing cells. The root tip has overlapping zones: where cells divide, elongate, or form different specialized cells. The root has three zones: the zone of cell division/meristematic, zone of elongation, and zone of maturation.  ZONE/REGION OF MATURATION ZONE/REGION OF ELONGATION ZONE/REGION OF MERISTEMATIC Zone of Cell Division/Meristematic - is a small region of actively dividing cells called the apical meristem. New cells are made here. Zone of Elongation - situated next to the meristematic region, where the cells grow, elongate and enlarge to make the root grow in length. Zone of Maturation - next to the region of elongation is the zone of maturation, where the cells mature and differentiate into a specific tissue 3. Root Hairs – they increases the surface area of the roots, improving absorption efficiency. They act like sponge underground, absorbing more nutrients and water. More root hairs means better water and nutrient uptake for the plant. 4. Primary Root - the first root formed from the embryonic root called radicle. 5. Lateral Root - root that develop or arises from the primary root. External Structure of the Roots 3 TYPES OF ROOT SYSTEM 1. TAP ROOT SYSTEM 2. FIBROUS ROOT SYSTEM 3. ADVENTITIOUS ROOT SYSTEM TAP ROOT SYSTEM is the primary and the main root that develops from the radicle, bears numerous branches and remains underground. It is usually found in dicots. Ex: sunflower, mustard, carrot and mango  FIBROUS ROOT in SYSTEM this root system, the primary root is short-lived sometimes non- existent. Are shallow and spread horizontally, hence cannot provide strong anchorage. Fibrous root system is the main root system of monocots. Ex: rice, grasses and wheat ADVENTITIOUS ROOT SYSTEM are roots that develop from any part of the plant except the radicle. They can be either aerial or underground.  These roots may grow from nodes (as seen in money plants and bamboo), stem cuttings (like in roses), tree branches (as in banyan trees), or the stem base (as in fibrous roots of monocots).