Question

Abnormal secondary growth is observed in
A. Dracaena
B. Wheat
C. Ginger
D. Rice

Answer 1

Hint:Abnormal secondary development, as in ancestral lignophytes, does not continue the pattern of a single vascular cambium containing xylem to inside and phloem to outside.

Complete answer
First we should know about secondary growth to answer this question. Secondary growth is the growth arising from cell division inside the cambia or lateral meristem and causing thickening of the stems and roots. Secondary growth occurs in most seedlings but typically monocots lack secondary development. It varies from the usual pattern of other seedlings if they have secondary development.
 Now, let us find the solution from the options-
->Vascular cambium is produced in certain members of plants such as Dracaena, Agave, Yucca, Lomandra, Aloe arborescens, Sansevieria, Kingia, etc. from the outer area of the soil tissues.
->Parenchyma produced by the vascular cambium to the outside and secondary vascular bundles developed to the inside.
->In certain plants the girth of the stern rises unchanged, like-Palm, Tulipa, Musa, etc. These plants are of a particular type of apical meristem. This is called primary meristem thickening.
->This apical meristem is accountable for the plant's growth both in length and girth (width). In Dracaena, however, irregular secondary growth is observed, and not in rice, wheat, and ginger.

Thus, the correct option is option (A) i.e. Dracaena.

Note:A significant characteristic of dicotyledons and gymnosperms is the creation of secondary vascular tissues from the cambium. In some monocots, after the primary growth is finished, the vascular tissues are also expanded but the improvement of these plants is of a different kind.