Since nitrogen is the most limiting nutrient for plant growth and development, plants living in low inorganic nitrogen environments needed to develop a special ability to take up organic nitrogen sources. Until now, alpine, boreal, arctic tundra plants, carnivorous plants, bromeliads, orchids and some agricultural plants have been shown to take up organic N under field and laboratory conditions. This adaptation can be exemplified by the high rates of organic N uptake and better growth of these plants when cultivated in the presence of organic N. Currently, transporters for amino acids have been found in many plant species, some of which related to the organs involved in the absorption of N, like roots, leaves and capturing organs of carnivorous plants. However, the ability to take up organic nitrogen sources might be widespread in the plant kingdom, which would allow for its economical use as fertilizers.