I have been discussing "gumi" on the Usenet newsgroup sci.lang.japan, and we appear to have determined that it is of the genus Elaeagnus, probably species pungens, closely related but not identical to the American silverberry E. commutata and the Russian olive or oleaster E. angustifolia. Unfortunately there doesn't appear to be any consensus on the English for it, so maybe we're better off just saying gumi in English, or Elaeagnus pungens if it fits the meter better...

Liland/haruo