Page 1 : 2)Macrosclercids — these are rod shaped structures, seen in the seed Coat of legumes., 3)Osteosclercids -are bone shaped, usually seen in seed coats and fruit walls., 4)Astrosclercids — are star shaped with irregularly projecting arms., , Function of sclerenchyma. Selerenchyma provides mechanical support., , ae Sclercids gives hardness to plant parts like seed coats, fruit walls etc., ‘bers are tremendous economic value.eg. mesocap of coconut is the basis of coir industry. Blast fibers, (phloem) of Corchorus capsularis, form the raw material in jute industry, , 6. Complex _or compound permanent tissue, , ‘© Complex tissue may be defined as a collection of different types of cells that performs a, common function. For example, Xylem and Phioem.Xylem is the water conducting tissue in, plants and phloem is the food conducting tissue in plants. Xylem and phloem constitute the, major components of vascular bundles. Therefore these are called the vascular tissues., Complex tissues is made up to more them one type of cells working together as a unit, Complex tissue is heterogenous in nature, and performs a common function eg. Xylem and, Phloem., , Xylem- On the basis of development xylem is of two kinds., , Primary xylem - Itis derived from procambiam during the formation of primary plant body developing, from embryo., , Secondary xylem: It is formed from cambium during secondary growth of plant development when, increase in thickness takes place., , Elements of Xylem/components of Xylem-Xylem is composed of four different kinds of elements., , 4. Tracheids — Itis a fundamental cell type of xylem seen in pteridophytes and gymnosperms. Tracheids, are spindle shaped elongated and dead cells. The thickenings ofthe cell wall are due to the deposition, oflignin. Xylem tracheids communicates each other through pits, , 2. Xylem vessels of tracheae- are the water conducting tissue in angiosperms. Cells are long tabular, vith ignified cell wals. Coss walls at both the ends are dissolved to form a pipe like channel. Vessels, are algo lignifed (annular, spiral, scalariform etc) and dead at maturity providing mechanical support, , 3. Xylem parenchyma - It is aso called as wood parenchyma. It is the simple parenchyma cells, esociated with xylem. it's main functions are storage of water and food materials, , Xylem fibers- These are the sclerenchyma fers associated with xylem. Xylem fibers provide mechanical, , strength to the specified parts,, , Phloem: [tis a complex permanent ssue meant for ranslocation of food materials Phloem occurs through, tutte plant body along with xylem. Phloem is made up of four types of els or companents, , 4.Sieve elements - Sieve elements consist of s. cells and s. tubes. In lower vascular plants sieve cells are, present while in angiosperms sieve tubes are present. Sieve tubes are formed of elongated living cells, arranged in vertical rows. The end walls of individual sieve tubes are perforated by number of pits. The end }, walls of siove tubes ar known as slave plates. A mature sieve tube of angiosperms is hawng vacuolated |