Tag: internal structure of stem(dicot and monocot)

Monocot plants, as the name suggests have only one cotyledon. these plants have characteristic features like fibrous root system because the radicle is short-lived, thus replaced by adventitious roots. They also have parallel-veined leaves and trimerous flowers.

Lysigenous intercellular spaces: These cavities of intercellular spaces store up water, gases and essential oils in them. The examples are commonly found in water plants and many monocotyledonous plants. The secretory cavities in Eucalyptus, Citrus and Gossypium are good examples.

In dicot stem, the lateral branches are exogenous in origin and they come out from the cortex of the stem. However, in dicot root, the lateral roots are endogenous in origin because they come out from the pericycle of the stem.

In a young dicot stem, the cambium is single layered. It is made by the intrafascicular cambium present within the vascular bundles and the dedifferentiation of the parenchyma cells of the medullary rays between the vascular bundles, called interfascicular cambium. Their combination gives a circular cambium that produces xylem elements on the inner side and the phloem elements on the outer side.

Cork cambium is secondary or lateral meristematic tissue that grows beneath the epidermis and replaces it in dicot roots and stems and is responsible for the secondary growth of the tree.

The pericycle is a thin layer located between the endodermis and phloem in plant roots. In dicot stems, it is located around the ring of vascular bundles in the stele. The nature of pericycle is sclrenchymatous. 

Bast fibers are made up of sclerenchymatous cells and are absent in primary phloem but present in secondary phloem of dicots and are elongated , unbranched and have pointed needle like apices and are devoid pf protoplasm at maturity and dead.

• Pericycle is a cylinder of parenchymal and sclerenchyma cells which lie just below the endodermis of the plants. 
• In dicot stem, the pericycle is heterogenous made of parenchyma and sclerenchyma alternatively in irregular patches but they are not multilayered.
• So, the correct answer is 'In a dicot stem, the pericycle is usually multilayered'.