Tag: internal structure of root, stem and leaf

A.Dicot stem – collateral, conjoint, endarch, open vascular bundles present in the form of rings.

B.Monocot stem – collateral, cojoint, endarch, closed vascular bundles present in the form of scattered manner in a ground tissue.

C.Dicot root – radial vascular bundles are present.

D.Monocot root – radial vascular bundles are present.

So, the correct option is ‘Monocot stem’.

I.Conjoint – applicable – because xylem and phloem are present side by side in the vascular bundles.

II.Endarch protoxylem – applicable – because protoxylem is present towards medulla side and metaxylem is present towards the pericycle side.

III.Open – not applicable – because, cambium is absent between the xylem and phloem in the vascular bundles.

IV.Phloem parenchyma is absent – applicable – in the phloem of monocots phloem parenchyma is not present.

So, the correct option is ‘III’

A.Bicollateral closed vascular bundles – Not present in any plants

B.Bicollateral open vascular bundles – found in the stems of Cucurbitaceae members

C.Collateral open vascular bundles – found in the dicotyledonous stems.

D.Collateral closed vascular bundles – found in the monocotyledonous stems.

So, the correct option is ‘Collateral closed vascular bundles’.

In monocot stem, epidermis, hypodermis, ground tissue, and vascular bundles are present. General cortex, endodermis, pericycle, medulla, medullary are absent. In the phloem, phloem parenchyma is also absent. Xylem and phloem are present on same radii, and also present side by side. So they are also called Collateral and Conjoint vascular bundles. In the vascular bundles, cambium is absent between xylem and phloem, So these are closed vascular bundles. In the xylem, protoxylem is towards the centre, and metaxylem is towards the periphery. So, it is an endarch xylem. 

The monocot stem shows the following characteristics: 

In monocot stems, the vascular bundles are dispersed. In dicot stems, the vascular bundles are arranged in ring.

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.