Question

Lysigenous cavity and ‘Y’-shaped xylem occurs in
A) Dicot stem
B) Monocot root
C) Monocot stem
D) Dicot root

Answer 1

Hint:Lysigenous cavities are intercellular spaces formed in plants due to the dissolution of complete cells. In the presence of these cavities, the vascular bundle containing the xylem and the phloem are enclosed within the cavity.

Complete answer:
The lysigenous cavities are responsible for the storage of water, gases and essential oils within them. The enclosure of the vascular bundles with the lysigenous cavity imparts a characteristic ‘Y’ shape to the arrangement of the vascular bundles with the xylem directed inwards and the phloem directed outwards.

The occurrence of these cavities is most often observed in aquatic plants as well as in monocot stems; as a result the ‘Y’ shaped xylem is also observed in monocot stems only.

Now, let us look at each option one by one.
A) The Dicot stem structure differs greatly from the monocot stem and it also does not contain any lysigenous cavities within its structure. Therefore, this option is incorrect.
B) Monocot root and monocot stem structure differ from each other. Unlike the stem, monocot roots do not contain Lysigenous cavities. Therefore this option is incorrect.
C) The monocot stem is known to contain lysigenous cavities which enclose the vasculature giving the water-transporting xylem a characteristic ‘Y’ shape. Therefore this option is correct.
D) The dicot root structure differs greatly from the monocot stem structure and it also doesn’t have any lysigenous cavities within. Therefore, this option is incorrect.

Thus, the correct answer is option (C) Monocot stem.

Note:Commonly, lysigenous cavities are observed in the oil producing cavities of eucalyptus, citrus secreting cavities of citrus fruits like oranges and limes and in Gossypium arboreum or tree cotton.