Ionic liquids have attracted considerable interest in various areas as new, non-volatile and non-flammable organic solvents, catalysts, reaction additives, ligands, drugs and other dedicated materials etc. Their general use, sometimes in bulky quantities, requires determination of their potential ecotoxicity on selected organisms. In the present work, influence of triphenylmethylphosphonium iodide (1) and triphenylhexadecylphosphonium iodide (2), introduced to soil, on germination and early stages of growth and development of superior plants was investigated using the plant growth test based on the OECD/OCDE 208/2006. In this test, the seeds of selected species, i.e. land superior plants - spring barley (Hordeum vulgare) and common radish (Raphanus sativus L. subvar. radicula Pers.) were planted in pots containing soil to which a test chemical compound had been added and in pots with control soil. To evaluate the phytotoxicity of ionic liquids 1 and 2 germination and weight (dry and fresh) of control plant seedlings were determined and compared with the germination and weight (dry and fresh) of the seedlings of plants grown in the soil watered with appropriate amounts of the test chemicals. The visual assessment of any types of damage to the test species, such as growth inhibition, chlorosis and necrosis, was also carried out and documented by digital photographs. Based on the obtained results, magnitudes of the LOEC - the lowest concentration causing observable effects in the form of reduction in growth and germination compared with the control and the NOEC - the highest concentration not causing observable, toxic effects - were also determined.