Assertion: fern's frond | /r/HasAspect | spore cases
Facets:
Source sentences:
text: Fertile fronds have spore cases (called sporangia ) that are usually grouped into clusters called sori on the back of the frond; sterile fronds do not.
text: Fertile fronds have spore cases (called ) that are usually grouped into clusters called on the back of the frond; sterile fronds do not.