Plant with unusual base fashionable, we hear (5,7)

'plant' is the definition.
The answer is an example.

'with unusual base fashionable we hear' is the wordplay.
I cannot really understand how this works, but
an anagram of 'with' is 'whit' which is present in the answer.
'base' could be 'e' (Euler's number - base of natural logarithms) and 'e' is present in the answer.
'fashionable' could be 'u' and 'u' is found within the answer.
This explanation may well be incorrect...

Can you help me to learn more?