Secondary xylem and phloem in dicot stem are produced by

Options

A. phellogen
B. vascular cambium
C. apical meristems
D. axillary merstems

Answer

B

Explanation

Secondary vascular tissues, i.e, secondary xylem and pholem are formed by the vascular cambium. It is produced by two types of meristems, fascicular or intrafascicular and interfescicular cambium. Intrafascicuiar cambium is a primary meristem which occurs as strips in vascular bundles.
It divides to form secondary phloem on outer side and secondary xylem on the inner side. Interfascicular cambium arises secondarily from the cells of medullaxy rays.
Phellogen or cork cambium is produced in the outer cortical cells of dicob stems, It is helpful in increasing the girth. Apical maristems are present at the tips of stem, root and their branches. They are responsible for increase in length of the plant. Axillary menistem is found in axillary buds. These cells are left behind from shoot apical mexistem during the formation of leaves and elongation of stems.