A concaved saw blade for tree felling apparatus adapted to be rotatably actuated through its center. The blade is inclined relative to the ground and is moved forwardly in a horizontal plane towards the tree to be cut. Saw teeth are adapted to be removeably mounted on the periphery of a rotatable saw blade of the flat or concave type. The teeth per se are made of a square head and a shaft extending rearwardly. The shaft is adapted to slide in a sleeve axially welded on the periphery of the saw blade. The shaft is adapted to be mounted in the sleeve in four different positions so that the head which is square and has a concave front face can make use of each of the four cutting edges surrounding the head for cutting trees.