HORTICULTURE

Detailed explanation-1: -The balloon shaped structures tracheal plugs formed in the xylem vessels of heartwood, due to the intrusions of secondary xylem parenchyma are called tyloses. So, the correct option is ‘Tracheal plugs which plug the lumen of the vessel and tracheids’.

Detailed explanation-2: -These are tracheal plugs found in heart wood, due to which the heart wood becomes non-functional. These are balloon-like swellings of xylem parenchyma cells in the lumen of vessels.

Detailed explanation-3: -In land plants, tyloses are spheroidal protoplasmic bulges that are generally formed when the adjacent parenchyma cells, axial parenchyma or ray cells, protrude into the dead axial conducting cells (Esau, 1965).