Abstract: A drip irrigation tube formed by longitudinally folding an elongated web having thick marginal side portions, and overlapping and sealing the thick marginal sides to form a tube. Discrete emitter elements are disposed at spaced intervals along the web and are formed by embossing or otherwise forming recessed emission grooves in one of the thick marginal edges so as to form a flow path from the inside of the tube to the outside. The emitter elements operate to provide a constant flow rate over a wide range of working pressures by controlled deformation and constriction of size of relatively short emitter passageways formed by a portion of the emission grooves.