Colleters are special types of multicellular trichomes. It is filled with sticky sticky substance. Digestive glands of insectivorous plants contain colleters. Punarnabha, Lemon, Rosa and Carya plants contain colaters.
(iii) Stigma: Unicellular, long, pointed and poisonous juice-filled trichomes are called Stigma. When the stinger comes in contact with the animal, the needle tip breaks and the poisonous juice is released. Skin burns due to toxic sap. Such as Tragia involucrata, Mucuna pruriens, Laportea aestuans, Agnichutra etc.
(iv) Scale: Special hair with thin coating is called scale. It is composed of sheets of flat, multicellular and disc-like cells. It reduces the rate of respiration.