Answer:
1. Cork Cambium
2. Vascular Cambium.
3. Xylem cells ; Phloem cells
4. Xylem cells
5. Xylem cells
Explanation:
In plants, growth is characterized by the elongation of the stem and roots. Woody plants also gradually increase is girth throughout their life times. Plant growth is divided into two types depending upon the two growth dimensions (height and width):
Primary Growth:
The elongation or increase in the lengths of the stem and roots is termed as primary growth. Primary growth occurs due to the rapid cell division at the shoot and root apical meristems. This rapid growth of the apical buds is called apical dominance and it prevents the development of lateral buds.
Secondary Growth:
Secondary growth is the increase in the thickness or width of the plant. This occurs due to the growth of lateral meristems i.e. the vascular cambium and cork cambium (in woody plants). Stem thickening occurs through the division of the vascular cambium located outside of the primary xylem and inside of the primary phloem. This division leads to the formation of the secondary xylem and phloem. The cells of the secondary xylem contain lignin and form the "woody" portion of the plant.
In woody plants, the cork cambium is the outermost lateral meristem and produces cork cells that provide strength and hardiness.