The name is in reference to the Satsuma mandarin. I have a satsuma tree in my backyard and they are common in the area. According to Wikipedia, Satsumas are from China but were introduced in the US by way of Japan.
The fruit is sold, only in season, in many groceries around the area. Also, it is a very popular homegrown citrus fruit grown in backyards and front yards like the Loquat, as irony to your question would have it, the Japanese plum.
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