A filamentous actinomycete, designated strain D65(T), was isolated from a root of a wild tree, Alnus nepalensis D. Don (Nepalese Alder), collected in Xishuangbanna, China. It produced the bioactive agents daidzein and N-acetyltyramine and had morphological and chemical properties characteristic of streptomycetes. Pink to brownish red diffusible pigments were produced on several ISP media. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain D65(T) formed a distinct phyletic line that was most closely, albeit loosely, associated with Streptomyces hebeiensis YIM 001(T), Streptomyces aurantiogriseus NRRL B-5416(T), Streptomyces griseoviridis NBRC 12874(T), Streptomyces niveoruber NBRC 15428(T) and Streptomyces thermovulgaris NBRC 13473. A number of phenotypic properties allowed differentiation of the strain from related Streptomyces species. Therefore strain D65(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces alni sp. nov. is proposed. The type strain is D65(T) (=CGMCC 4.3510(T)=NRRL B-24611(T)).