Assertion: buckwheat's seed | /r/HasProperty | three-sided achene
Facets:
Source sentences:
text: The seed of buckwheat is a three-sided achene that is smooth, shining, and 5 mm long (Munz, 1973).
text: Seed or fruit of the plant are three sided, and smooth.
text: Each seed is a three-sided achene, often with a round tubercle on one or all three sides.