Which of the following statements is true? (a) Vessels are multicellular with wide lumen. (b) Tracheids are multicellular with narrow lumen. (c) Vessels are unicellular with narrow lumen. (d) Tracheids are unicellular with wide lumen.
Option D Xylem is the principal water conducting tissue of the plant. It consists of four types of cells tracheids, vessels, xylem fibres and xylem parenchyma. The tracheids and vessels together are known as tracheary elements. Tracheids are characteristic of all vascular plant. Tracheids originate from single cells. These are single elongated cells with tapering ends. The end walls are without perforations. Their length varies from 1 to 3 mm. Tracheids are devoid of protoplast, hence dead; fairly large cavity of these cells is without any contents. The wall of tracheids is moderately thick and usually lignified.
