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The species Parkinsonia aculeata L. occurs in arid, semiarid and subhumid zones around the world, where it is used in different proposes. However, in certain environments, as for example, caatinga and associated ecosystems in the Northeastern Brazil, the species has an invader behavior. Thus, an experiment was conducted under greenhouse conditions to evaluate the effects of salinity on the germination behavior and vegetative growth of Parkinsonia aculeata. Initially, the material of an Ultisol was irrigated with saline water (0.2, 1.5, 3.0, and 4.5 and 6.0 dS m(-1)). Then, they 16 kg of each substrate were placed in 21 L plastic pots. The treatments were arranged in randomized blocks with nine replicates. After emergence, 10 days after sowing, thinning was carried out, leaving four seedlings per pot. The variables evaluated were the following: emergency; emergency speed index; concentrations of chlorophyll a, b and total; stem diameter at ground level; height and number of leaves 69 days after sowing. The increase in soil salinity from not saline (CEes < 2 dS m(-1)) to slightly saline (4 dS m(-1) > CEes > 2 dS m(-1)) and moderately saline (8 dS m(-1) > CEes > 4 dS m(-1)) has stimulated the emergency, the initial growth and chlorophyll production in Parkinsonia aculeata plants, unlike what occurs with most of the species. This partially explains the success of their proliferation in certain sites in the caatinga.