Question

What happens in plants during vascularisation?
A. Differentiation of procambium, the formation of primary phloem followed by the formation of primary xylem
B. Differentiation of procambium followed by the formation of primary phloem and xylem simultaneously
C. Formation of procambium, primary phloem, and xylem simultaneously
D. Differentiation of procambium followed by the formation of secondary xylem

Answer 1

Hint: The development of vascular bundles results from meristematic tissue concerned with providing the primary tissues of the vascular system. This tissue is located next to the protoderm. It gives rise to complex tissues later.

Complete answer: The process of formation of vascular tissues such as xylem and phloem from the vascular bundles that result from procambium is called vascularisation. The mother tissue that forms the vascular tissue is called the cambium. The cambium turns into elongated procambium strands during the primary growth phase of plants. The procambium then differentiates into xylem which is followed by the formation of phloem.
a) The procambium differentiates into primary phloem first and then moves toward the formation of primary xylem. But both primary xylem and phloem form simultaneously and not serially.
b) The procambium is already formed in the vascularisation phase. It only gets specialized or gets differentiated into primary phloem and xylem.
C) The formation of secondary xylem occurs only after the formation of vascular cambium during the secondary growth phase. It is not formed from procambium.
Thus, the correct option is option B.

Note: We know that vascularisation plays an important role in plant development as it results in vascular tissues that help in the transportation of water and minerals. It should not be confused that procambium differentiates into primary phloem and xylem and does not directly convert into one of the vascular tissue forming the other.