Assertion: grass pollen | /r/HasProperty | difficult to classify
Facets:
value: very
type: DEGREE
Source sentences:
text: There are several classic examples of this, including Picea (spruce) and Quercus (oak) pollen, which are both extremely difficult to classify below the genus level, and Poaceae (grass) pollen, which is very difficult to classify at a taxonomic rank below family (Mander et al.