buckwheat: [16] Buckwheat has no connection with male deer. The buck- element is related to the English word beech, and the name comes from the resemblance of buckwheat (the seeds of a plant of the dock family) to the three-sided seeds of the beech tree. The word was actually borrowed from Middle Dutch boecweite, meaning literally ‘beechwheat’. => beech[buckwheat etymology, buckwheat origin, 英语词源]
1540s, from Middle Dutch boecweite "beech wheat" (compare Danish boghvede, Swedish bovete, German Buchweizen), so called from resemblance between grains and seed of beech trees. Possibly a native formation on the same model as the Dutch word, from a dialectal form of beech. See beech + wheat.