Salt settling over the outer, moist, absorbent openings of tiny pores on leaves (8)

'tiny pores on leaves' is the definition.
I can't tell whether this definition defines the answer.

'salt settling over the outer moist absorbent openings' is the wordplay.
'settling' indicates anagramming the letters (settle can mean to solve or sort out).
'over' is an insertion indicator.
'openings' suggests taking the first letters (I've seen 'opening' mean this).
The first letters of 'the outer moist absorbent' is 'toma'.
'salt' is an anagram of 'stal'.
'stal' placed around 'toma' is 'STOMATAL'.

'of' acts as a link.

Can you help me to learn more?