In order to identify the constituents of ethanol-extractable amino acids from Pinus densiflora SIEB. et ZUCC. leaves, high performance liquid chromatography (JASCO TWINCLE amino acids analyzer system) was used. According to the results obtained, ethanol-extractable amino acids confirmed to be such 19 different kinds, as Asp, Thr, Ser, Asn, Glu, Gln, Pro, Gly, Ala, Val, Met, Ile, Leu, Tyr, Phe, Lys, His, Arg and γ-aminobutyric acid (GABA). There was a seasonal fluctuation in the amount of free amino acids constituent, and three different patterns of changing in the amount were noticed. The major constituents of free amino acids were found to be GABA and Ala. There were similarities in the patterns of free amino acids contents among new buds, one year leaves and two year leaves. However few amount of Met and His were detected from the stage of the new buds than any other. Basic amino acids were found more in the one year leaves and the two year leaves than in the new buds. The contents of Gln, Lys and Arg increased in the germination stage of the new buds, and the contents of GABA, Pro, Ala and Asn decreased in the growing stage of the new shoots. The above facts lead to the conjecture of that these free amino acids were involved deeply in the growth of Pinus densiflora SIEB. et ZUCC. leaves.
