HSEB Notes on Internal Structure of Monocot Root
Class : 12
Monocot root lacks of secondary growth and shows following internal structures:
EPIDERMIS
It is composed of a thin walled,compactly arranged single layer of parenchymatous cells without intercellular space.it also gives rise to unicellular root hair.cuticle and stomata are absent in monocot root. epidermal cells and root hair take part in absorption of water and minerals from soil. multilayer epidermis is found in epiphytic plants like orchid and is called as velamen.pnematodes of velamen help in gaseous exchange.
CORTEX
It consist of layers of parenchymatous cells having intercellular spaces. cells are oval in shape and help in gaseous exchange.they help in starch storage too. in maize,outer layer of cortex changes into exodermis or hypodermis. exodermis is protrctive in nature.
ENDODERMIS
Endodermis isthe innermost layer of cortex.it consists of single layer of closely packed barrel shaped parenchymatous cells. the cells are characterised by the presence of casprian strips in their radial walls.they are formed by the deposition of suberin and lignin.endodermis opposite to protoxylem are thin walled and are called as passage cells. it allows the radial diffusion of water.
PERICYCLE
It lies below the endodermis and forms the outer boundery of primary vascular tissue.it is usually single layered and sometimes multilayered.it may be parenchymatous or sclerenchymatous . it gives rise to lateral roots.
VASCULIAR BUNDLE
The vascular bundles are of radial type.xylem and phloem are radially arranged alternating with each other .they are 8-20 in number.xylem shows exarch condition.metaxylem vessels are larger with spherical and pitted thickening.protoxylem have smaller vessels and with annular thickenings. Phloem contains all component except bast fibre.xylem help in conduction of water and minerals while phloem helps in conduction of food materials.
CONJUNCTIVE TISSUE
It is found between xylem and phloem bundles.maybe parenchymatous or sclerenchymatous.
PITH
It is central part of root and lies internal to vascular bundle.it is made up of thin walled parenchymatous cells with intercellular space.it is well developed in monocot root.
Read this also :
- DNA Replication Process | HSEB Notes of Botany Class 12 Biology
- Physiology of Digestion | Class 12 Zoology Notes
- Digestive Grands Associated with Alimentary Canal of Human | Class 12 Biology Notes
- Alimentary Canal in Digestive System of Human Beings | HSEB Notes Class 12 Zoology
- Physiology of Respiration | HSEB Notes of Biology Class 12
- Difference between Inhalation and Exhalation | Class 12 Biology Notes
- Respiratory Organs and Mechanisms of Breathing | HSEB Notes of Biology Class 12
- Respiration and Its Types | HSEB Notes of Biology Class 12
- Urine Formation | HSEB Notes of Biology, Zoology Class 12
- Structure of Kidney and Nephron | HSEB Notes of Biology Class 11 Zoology
- Physiology of Excretion | HSEB Notes of Biology Class 12 | Zoology
- HSEB Notes on Venous System of Circulatory System of Human Beings Class 12
Don't forget to LIKE, SHARE and COMMENT. Please Join with us on Facebook and Google + For daily notes
No comments:
Post a Comment
Don't forget to leave your comment.