Australian native flora was examined with nuclear magnetic resonance (n.m.r.) techniques for its content of nitrogenous compatible solutes. Plants were sampled from four habitats: two arid, one subhumid, and one saline estuarine marsh. Eight and two of the 15 plants in the subhumid area accumulated proline and glycinebetaine, respectively, whereas many of the plants in the two arid habitats accumulated these solutes. With only two exceptions plants in the saline marsh could be described as either proline accumulators (six species) or glycinebetaine accumulators (eight species). Attempts to correlate the glycinebetaine and proline contents with the relative water content (RWC) were not successful. Some plants accumulate compounds other than, or in addition to, proline or glycinebetaine, such as trans- 4-hydroxy-N-methyl-L-proline, which was accumulated in Melaleuca lanceolata. Exocarpos aphyllus accumulated an as yet unidentified compound.

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