Practical General Biology

Practical General Biology The Stem , The Root and The Leaf 2012_2013

The Stem Function of Stem :Stems support photosynthetic leaves and reproductive structures, thus increasing photosynthetic and reproductive efficiency. Stems supply water and minerals to shoots . The Dicotolydonous Stem (Dicot stem)Component of dicot stem :Epidermis, ground tissue (paranchyma, collenchyma, sclerenchuma, cortex, pith), vascular tissue (xylem, phloem ).Protoxylem vessels : are the smallest vessels, their typical location is towards the pith. Metaxylem vessels: are the larger vessels, their typical location is towards the cortex. Fascicular cambium : is the area between the primary xylem and phloem . Organization of bundle .The Dicotolydonous Stem (Dicot stem)

The Monocot Stem Component of monocot stem : Epidermis, ground tissue (paranchyma, collenchyma, sclerenchuma), vascular tissue (xylem, phloem ).Random arrangement of the vascular bundles, and its surrounding by sclerenchyma . Not have secondary growth. Xylem the same of V.No have cortex and pith .No have cambium layer .

The Monocot Stem

The Root The Monocot Root A count of metaxylem if this above 8 its monocot root .The roots of monocots are organized into a cortex, with primary xylem and primary phloem in central pith . Not have secondary growth, because absent of cambium .The area of pith are largest, and the phloem is combination with protoxylem .Thicker from one side and have Casparian .

The Dicot Root Number of vascular bundle from 4 to 5 only .Have secondary growth and cambium its present . Not have pith .Phloem arrangement with xylem arm to formation vascular bundle .Thicker form all side .Have passage cell .

The Leaf The Monocot Leaf The vascular bundle its spread in the leaf .Not differentiation of Mesophyll .Distribution of Stomata its equal in the upper and lower of leaf .Vascular bundles are enclosed by scalarenchyma . Stomata are damples shape .Have buliform cells . Xylem are V shape .venation in the leaf blade : Parallel venation .

The Dicot Leaf Stomata are distribution in lower more than in upper.Stomata are kidney shape .Have not buliform cell in upper epidermis . Mesophyll is homogenus and are distinguished between Palisade and Spongy paranchyma. Vascular bundles are large and central and phloem is toward the lower epidermis . The collenchyma present in upper and lower .Waxy layer in upper epidermis are thicker .Waxy layer in lower epidermis are thinner, because have stomata .Have not scolarenchyma .Venation in the leaf blade : Network venation .

Good Luck