Special Type of Tissue - Plant Anatomy PDF

Special type of tissue/ secretary or excretory tissue These are the tissue formed for storage of secretary or excretory products. These products are kept in form of cavities which are of: 1. 2. 3. 1. i. ii. 2. Glands or glandular tissue: these are secretary tissue which sectretes gum, o...

Special type of tissue/ secretary or excretory tissue These are the tissue formed for storage of secretary or excretory products. These products are kept in form of cavities which are of: 1. 2. 3. 1. i. ii. 2. Glands or glandular tissue: these are secretary tissue which sectretes gum, oil, mucilage tannins, resins. The gland may be internal or external. Anatomy of dicot root **(i) Epiblema: **It is the outermost single layer of barrel shaped thin walled parenchyma without intercellular space.** **Cuticle and stomata are absent. Unicellular root hairs are present which helps in absorption of water and mineral. It is also known as **Rhizodermis **or**Piliferous layer**. **(ii) Cortex: **It is a multilayered large zone** **made of thin-walled parenchymatous cells with intercellular spaces. It stores food and water. **(iii) Endodermis: **It is the innermost layer** **of cortex. The cells are barrel - shaped, closely packed,without intercellular space. The cells opposite to phloem posses an internal strips orbands of suberin or lignin called **casparian strips**. It preventwall to wall movement of substances between cortex and pericycle. The cells opposite to xylem are thin walled and called passage cells. It helps in the movement of** **water and dissolved salts from cortex into xylem. So it is also called the biological check post. **Iv ) pericycle**: it lies below endodermis and consists of thin walled parenchyma without intercellular space. It helps in formation of vascular cambium, cork v) **vascular bundle:** it lies inner to pericycle and is radial type ie xylem and phloem are arranged alternately. They are 2-6 in number. Xylem is exarch in condition with protoxylem lies at periphery and metaxylem towards the centre. Xylem consist of vessel, tracheids, xylem parenchyma and xylem fiber. It helps in conduction of water and minerals. Phloem consists of sieve elements, companion cells, phloem fiber and phloem parenchyma. It helps in conduction of food. vi\. conjunctive tissue: in between xylem and phloembundles there are presence of thin walled elongated parenchyma without intercellular space called conjunctive tissue. They helps in storage of food. Vii. pith : pith is reduced or absent. If present made of thin walled parenchyma with or without intercellular space. It helps in storage of food. https://img.brainkart.com/imagebk40/s5Ak5fK.jpg