(a) Exarch Protoxylem

Endarch Protoxylem

When the protoxylem is present towards the periphery and metaxylem towards centre in vascular bundle as it is found in roots.

If the protoxylem is present towards the centre and metaxylem towards periphery in the vascular bundle as it is found in stem.

(b) Stele

Vascular Bundle

Stele refers to conducting tissue or the central part of root or stem in plants. It comprises of vascular tissue, ground tisssue and pith and limiting boundaries, i.e., endodermis and pericycle

Vascular bundle comprises of vascular/conducting tissues xylem and phloem. Sometimes cambium is also included as in dicots.

(c) Protoxylem

Metaxylem

It is the first or earlier formed xylem. Matures before the gorwth and differentiation of plant organs. Protoxylem elements are smaller in diameter. Tyloses absent in protoxylem vessels. Fibres are absent.

It is the later formed xylem. Matures after the growth and differentiation of plant organs. Metaxylem delements are broader and greater in diameter. Tyloses are generally present. Fibres may be present.

(d) Intrafascicular Cambium

Inter fascicular Cambium

Cambium present in between the primary xylem and primary phloem is called-intra fascicular cambium,as in dicot stems.

The cambium present in between the two vascular bundles making the cambium continuous and forming a completering of cambium is called interfascicular conbium.

(e) Open Vascular Bundle

Closed Vascular Bundle

Cambium present in between the xylem and phloem tissue.

Intrafascicular cambium between the phloem present. Occur in the stems of dicot and gymnosperms. May be collateral or bicolateral. Xylem and phloem not in direct contact with each other due to cambial string. Intrafascicular cambium results in secondary growth. Cambial activity produces secondary phloem and secondary xylem that push primary phloem and primary xylem away from each other.

Cambium is not present in between the xylem and phloem tissue.

Intrafascicular cambium absent. Occur in leaves and monocot stems. May be collateral or concentric, Xylem and phloem are in direct contact due to back of cambial string. No such activity found. No such activity found.

(f) Root Hair

Stem Hair

Root hairs are unicellular

It increase the surface area of root for absorption of water and minerals.

Stem hairs are multicellular

They are epidermal outgrowths known as trichomes.

They help in preventing water loss due to transpiration.