Daniel, we have Decaisnea fargesii, which looks almost identical. Do you have any information on the exact difference(s) between the two species? TIA.
Chris, Decaisnea insignis Hook f. & Thoms. 1854 is synonymous with D. fargesii Franch. 1893. Priority goes to the earlier, validly published name.
Re: Decaisnea insignis - Decaisnea fargesii Here are flowers on what I assume is the same tree. The interpretive sign has a different introduction now, with a different decision on the name.
According to some books, they are separate species, differing mainly in mature fruit colour, yellow in D. insignis, blue in D. fargesii, and coming from separate regions (D. insignis from Nepal, D. fargesii from SW China). Whether that really is a significant difference is open to dispute. D. insignis is also noted as being rather less winter-hardy (e.g. not hardy in most of Britain, whereas D. fargesii is). Maybe some day, someone might get round to doing genetic tests to see how they compare in DNA.