This is a device to catch insects for fulfilling the deficiency of nitrogen in the medium where plant is growing. In case of Nepenthes, Dischidia and Sarracenia leaf-lamina is modi­fied into pitcher-like structure called leaf-pitcher.
Nepenthes also called pitcher-plant bears special type of leaves. Leaf-base is winged, petiole is tendrillar and lamina is modified into pitcher-like structure having a coloured lid which attracts the insects and keeps the pitchei closed during immaturity. The rim of the pitcher is internally lined by backwardly directed hair and a large number of minute scales due to which the insect slips and is captured.
The inner walls of the pitcher have glands which secrete a digestive fluid into the cavity of the pitcher. The insect is digested here and waste material settles down at the bottom. Sarracenia has pitchers in the from of rosetts. The pitchers are similar to those of Nepenthes but are sessile.
Pitchers are also found in Dischidia, an epiphytic climber. Rain water and debris accumulate inside the pitchers. The roots from the nodes of the stem grow into the cavity of the pitcher and absorb water.