HORTICULTURE

Detailed explanation-1: -The cambium produces new layers of phloem on the outside and of xylem on the inside, thus increasing the diameter of the stem. In woody plants, this process produces wood and shapes the plant into a tree with a thickened trunk.

Detailed explanation-2: -The thickening of the stem that occurs in secondary growth is due to the formation of secondary phloem and secondary xylem by the vascular cambium, plus the action of cork cambium, which forms the tough outermost layer of the stem. The cells of the secondary xylem contain lignin, which provides hardiness and strength.

Detailed explanation-3: -Secondary growth refers to the growth that results from cell division in the cambium or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate and gives rise to primary tissue.

Detailed explanation-4: -The vascular cambium, which produces xylem and phloem cells, originates from procambium that has not completely differentiated during the formation of primary xylem and primary phloem.