EVERYDAY SCIENCE

Detailed explanation-1: -The secondary growth of plants increase in stem thickness and it is due to the activity of the lateral meristems, which are absent in herbs or herbaceous plants. There are two types of lateral tissues involved in secondary growth, namely, vascular cambium and cork cambium.

Detailed explanation-2: -The Vascular Cambium and Secondary Growth. The vascular cambium and cork cambium are secondary meristems that are formed in stems and roots after the tissues of the primary plant body have differentiated. The vascular cambium is responsible for increasing the diameter of stems and roots and for forming woody tissue.

Detailed explanation-3: -Cambium (lateral meristem) is situated below the bark and is responsible for the increase in the girth of the stem or root.

Detailed explanation-4: -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-5: -Apical meristems give rise to the primary plant body and are responsible for the extension of the roots and shoots. Lateral meristems are known as secondary meristems because they are responsible for secondary growth, or increase in stem girth and thickness.