Objective The morphological characteristics and 6 kinds of medicinal composition of leaves in Acer truncatum were analyzed to provide the reference for the qualitative and quantitative detection of flavonoids and phenolic compounds, development and utilization of leaf tea, and selection of superior clones in A. truncatum.

Method The morphological indexes of the leaves were determined by conventional methods. The medicinal constituents of the leaves were detected by ultrasonic extraction and HPLC.

Result The variability of leaf morphology was petiole length > leaf lobe width > leaf lobe length > leaf length > leaf width > leaf base angle. The leaf lobe width was mostly 2-3 cm. The leaf base-angle was less than 180°, except for No. 6-1. The average contents of quercetin, kaempferol, isorhamnetin, catechin, chlorogenic acid, and caffeic acid in leaves were 2 979.65, 1 474.92, 268.12, 1 380.18, 218.28 and 8.13 μg·g^-1 respectively. The correlation coefficient between the petiole length and the chlorogenic acid content in the leaves was -0.735^*. The correlation coefficient of two tested leaf medicinal materials between mother and its asexual young plants of 'Luhong No.1' was 0.914^*. The flavonoids content of No.6 series were higher than that of the others, while the phenolic content of No. 1 series was higher than that of the others. There were also significant differences of medicinal component content among different families, even different clones in the same family.

Conclusion The indirect selection can be used for breeding leaf supply lines in A. truncatum, for example, the chlorogenic acid content of leaves could be improved by selection of petiole length. The selection of higher medicinal content individuals at young age is feasible because of the positive Juvenile-Mature Correlation of leaf medicinal component content.The significant differences of the leaf medicinal composition among clones in the same family reveal that individual plant selection in the family is also necessary. The line 'Luhong No.1' can be considered as high quality strain resource both for medicinal and ornamental usages due to its larger leaf, higher content of medicinal materials, and the red leaf color in autumn.