$\Rightarrow$ In a maize leaf, group of $5$ to $7$ cells without chloroplasts and cuticle of large size are located at certain distances in upper epidermis in which small and slanted, unicellular trichomes are located on both lateral sides.

$\Rightarrow$ When moisture decreases and dryness increases in atmosphere then mechanical cells lose water. So cells lose turgidity, leaf lamina curls. Thus due to decrease in area of leaf lamina, transpiration is prevented. These cells smell by absorbing water in humid atmosphere. So leaf is exposed. So these cells are also called water absorbent cells.

$\Rightarrow$ Thus these cells induce movement of leaves so they are also called mechanical cells.

$\Rightarrow$ Thus bulliform cells are seen in a maize leaf.