Many attempts have been made to use absolute biometric values as accessory specific characters in cereals and grasses. The present note is an attempt to express by plain graphs not only the absolute average lengths but also the relations of length between the internodes of the culm.In some cases, the graphic representation leads to a simple mathematical formula; in others this is not possible, but the shape of the graph gives interesting information on the role played by the young inflorescence during the growth of the culm. Sterile or, on the contrary, hypersexual culms have the history of their youth inscribed in their adult structure.The observations in the present paper will be connected with a larger study of the conditions of growth and mode of differentiation of the plant tissues. Relations with the peculiar structure of the epidermis of the culm are discussed.