Question

The balloon-shaped structures called tyloses

• A. are linked to the ascent of sap through xylem vessels
• B. originate in the lumen of vessels
• C. characterize the sapwood
• D. are extensions of xylem parenchyma cells into vessels

Answer 1

The correct option is D are extensions of xylem parenchyma cells into vessels

Tyloses are the balloon-like ingrowth of parenchymatous cells in the lumen of xylem vessels of the heartwood.

Heartwood is a part of the secondary xylem formed during secondary growth. The cavities of heartwood vessels and tracheids get blocked by tyloses and these xylary elements are rendered non-functional.

Tyloses can help plants in defending themselves against pathogens. They clog the vessels and check the advancement of the pathogen to other parts of the plant.