List of identifying features of t.s monocot stem and dicot stem?
Typical monocotyledonous stems shows following characteristics: Circular stem, may have depressed structures due to the presence of lateral branches Have thick cuticle, single layered epidermis and epidermal hairs are absent Single layered cuticularised epidermis may contain multicellular trichomes Ground tissues are not differentiated into cortex and pith Hypodermis is generally sclerenchymatous It has no distinct endodermis and pericycle Epidermis contains stomata with guard cells. Scattered vascular bundles are surrounded by sclerenchymatous bundle sheath cells and called atactostele Each vascular bundle is oval, conjoint, collateral and closed There is no distinction between pith and pith rays Xylem is endarch, phloem is represented only by companion cells, seive tubes and little phloem fibers ––––––––––––––––– Typical dicot stem show following characteristics: Presence of well-defined epidermis with cuticle and multicellular stem hairs. Cortex has collenchymatous hypodermis regularly or as discontinuous patches. Endodermis is distinct as the innermost layer of the cortex. Pericycle composed of parenchyma and sclerenchyma alternately as irregular patches (heterogenous). Vascular bundles are conjoint, collateral, endarch, open and arranged in a ring surrounding pith (eustele). The center of pith is made from thin walled parenchyma cells with distinct intercellular spaces. Pith rays or medullary rays are found as separator of two vascular bundles.