It’s a perennial controversy among friends who are docents in a local garden: what is the proper common name for Prunus mume? Is it Japanese apricot, or Japanese plum? Our interpretive materials go back and forth between the two over the years.
With common names, there are no definitive answers. Genetically, Prunus mume is closer to apricots, as this article in Curtis’s Botanical Magazine (v.39, no. 3, September 2022) indicates: “P. mume is classified within subgenus Amygdalus alongside almonds and peaches and sits within section Armeniaca, being most closely related to P. armeniaca and P. sibirica (Yazbek & Oh, 2013).” (Those species of Prunus are both types of apricot.)
However, cultural context is also important. Although the plant originated in China, it was introduced in Japan in the sixth century C.E. Since the garden is focused on plants that are traditional to Japan, you should probably include both plum and apricot in your interpretive materials, as this Seattle Japanese Garden blog post does. Japanese new year decoration includes sho-chiku-bai, a trio of plants which are pine-bamboo-plum or apricot, depending on the English translation. (In China, this same trio of plants is referred to as the Three Friends of Winter because of their resilience during this season.) Which common name you give primacy will be a judgment call. In their book, Garden Plants of Japan, Ran Levy-Yamamori and Gerard Taaffe refer to the English name as follows: “Japanese apricot (sometimes confusingly referred to as Japanese plum).”