The Apricot tree, Prunus armeniaca L., has a rhythmic, definite growth with sympodial branching. A stochastic modelling of basic processes which contribute to growth unit (G.U.) construction, namely growth and death of apical meristems, is proposed. At spring growth, the number of metamers formed per time unit fits a Poisson distribution which evolves smoothly towards a more narrow distribution. The growth process is modelled by the Renewal theory. A hypothesis on meristematic activity explain these results. The final number of metamers per G.U. is modelled by a mixture accounting for both growth and death processes. Axillary shoots are found all along each G.U., displayed according to acrotony. Branching is modelled by a two states Markov chain.