Biology XI:6 Anatomy of Flowering Plants(4 Anatomy..Dicot & Monocot

Anatomy of Dicot and Monocot Plants Dicot and Monocot Root Tissue organization Dicot Monocot Figure Epidermis Has a single layer of epidermal cells, some of which protrude to form root hairs Same as that of dicot root Cortex Has several layers of thin-walled parenchymatous cells, with intercellular spaces Same as that of dicot root Endodermis Single layer of barrel-shaped cells, without intercellular space, and contains Casparian strips (water impermeable layer consisting of waxy suberin) Same as that of dicot root Pericycle Has thick-walled parenchyma In these cells, initiation of lateral cambium and vascular bundles responsible for secondary growth takes place. Secondary growth is absent in monocots. Pith Small and inconspicuous Large and well-developed Vascular bundle Single (Monoarch) More than six (Polyarch) Conjunctive tissue − These are the parenchymatous cells that lie between xylem and phloem. On maturity, cambium rings develop between xylem and phloem. Stele − structure represented by all tissues on inner side of endodermis such as pericycle, pith, vascular bundle Dicot and Monocot Stem Tissue organization Dicot stem Monocot stem Figure Epidermis Covered by cuticle Same as dicot stem Cortex (divided into three parts) Hypodermis Cortical layer Endodermis Contains few layers of collenchymatous cells Contains parenchymatous cells with conspicuous intercellular spaces Rich in starch Contains few layers of sclerenchymatous cells - Rich in starch Pericycle On the inside of endodermis and above the phloem in the form of semi-lunar patches of sclerenchyma Same as dicot stem Vascular bundle These are arranged in a ring. This arrangement is a characteristic of dicot stem. They are conjoint, open, and have endarch protoxylem. Vascular bundles are scattered and closed with peripheral bundles being smaller than central. Phloem parenchyma is absent and water containing cavities are present. Pith Present Absent Dicot and Monocot Leaf Tissue organization Dicot leaf (Dorsiventral) Monocot leaf (isobilateral ) Figure Epidermis Covers both upper (adaxial - bearing less/no stomata) and lower (abaxial -bearing more stomata) surface of leaf and bears a cuticle Stomata present on both sides Mesophyll Differentiated into palisade (has parallel arranged elongated cells) and parenchyma (with loosely arranged oval/round cells); it possesses chlorophyll Not differentiated into palisade and parenchyma Vascular Bundle Present in midrib and veins (reticulate venation); surrounded by bundle sheath cells Leaves have parallel venation. Bulliform cells (modified epidermal cells) are present along the vein which absorb water and make the cells turgid.