Assertion: cambium | /r/HasProperty | difficult
Facets:
value: practically
type: DEGREE
value: to distinguish the initials
type: PURPOSE
Source sentences:
text: Theoretically, the cambium is a single layer of cells, called initial cells; practically, it is difficult to distinguish the initials from their still-undifferentiated daughter cells, and several cell layers are collectively called the cambium, or cambial zone.