Q.Grafting is successful in dicot plants but not in monocot plants because the dicot plants have :

Spring wood forms because the cambium is highly active in spring, laying down many wide-cavitied xylem vessels — so (i) is false while (ii) and (iii) are true.

The activity of the vascular cambium varies with the season, and this seasonal variation is exactly what produces the annual growth rings seen in a woody stem's cross-section.

Check each statement:

1. "is less active" — this is FALSE. In spring, water and nutrients are abundant and conditions favour active cell division, so the cambium is at its MOST active, not least active.
2. "produces a large number of xylary elements" — this is TRUE. Because the cambium is dividing rapidly, it cuts off many new xylem (and phloem) mother cells in a short time. …

Grafting succeeds in dicots because their vascular cambium can proliferate at the cut surface and physically join the stock and scion's conducting tissues, a capacity monocots lack.

Grafting is a method of vegetative propagation in which the cut surface of a stem piece from one plant (the scion) is joined to the cut surface of a rooted plant (the stock) so that their tissues fuse and grow as one plant. Success depends on the cambium: in dicot stems, a ring of vascular (lateral) cambium lies between the xylem and phloem, and this meristematic tissue is actively dividing. When two dicot cut-surfaces are pressed together, their cambial cells proliferate, form a callus, and differentiate into new xylem and phloem that bridges the two pieces, restoring continuous vascular connection.

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