.Trichomes or plant hairs is elongate tubular out growth in epidermal cells , the base is embedded in the epidermal cell is the foot , the free project portion is the body which is characteristic feature for leaves of senna and Digitalis .o The cutin is an aggregate of modified condensed or oxygenated fatty acids known as cutinogenic acids .The epidermal cells may be extend outwards as conical projection called papillae as in coca and senna leaves .