Hint: The meristematic tissues in plants are primarily responsible to promote growth by active cell division.
Complete answer: The tissue responsible for the rapid growth of the lawn grass is meristematic tissue and intercalary meristem. Meristematic tissue is a group of cells that are capable of continuously dividing and hence they result in the formation of new cells at a fairly fast rate. They are highly metabolically active cells. Based on their position in the plant’s body, meristematic tissue is further classified into:
1) Apical meristem: Like the name suggests, it is present in the apices of primary and secondary shoots and even found in the roots also. It is primarily responsible for the increase in length of the plant body.
(2) Intercalary meristem: This tissue is majorly located between the regions of the permanent tissues. Intercalary meristems are efficiently capable of cell division and they promote the rapid growth and especially regrowth of many monocots including grass. Intercalary meristems at present at the base of grass leaf blades which explains their rapid elongation, as well as the quick recovery rates of the damaged leaves to rapidly regrow.
(3) Lateral meristem: It is present along the side of organs of the plants. In angiosperms, intercalary meristems occur only in monocot in particular, grass stems at the base of nodes and leaf blades.
Note:The intercalary meristem is basically responsible for replenishing the areas which have been over grazed by cattle.