Formally yields the propagative parts of the plant we say (5)
I believe the answer is:
cedes
'formally yields' is the definition.
'cedes' can be an answer for 'yields' ('cede' can be a synonym of 'yield'). I am not sure about the 'formally' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for cedes that I've seen before include "Surrenders or relinquishes" , "Yields, hands over" , "Gives way" , "Surrenders or yields" , "Gives in, relinquishing" .)