Ev 1605 Parsing Help Please

[JJ109]

I think these are my last two. Each clue has a superfluous letter

15d Funeral ode that is driven by decreased turning up under extreme pressure (7)
The answer is EPICEDE (a funeral ode), I can see parts of the parsing but not all of it

20d Plants in vase at last overcoming introduction of parasites (8)
I have S _ M _ IRES
I think it is sampires (plants) but can't parse the rest.

Thankyou - this puzzle has done my head in and it is getting late, so I shall respond in the morning. Many thanks!

[JJ109]

Why is it as soon as I have posted I have seen the parsing for 15d?
Thesurplus letter is the D of Driven
Therefore ie (that is) "riven / split" by dec(reasing) reversed
= icede
following ep (extreme pressure)

Therefore the superfluous letter in 2d is likely to be an E

[Neveracrossword]

Well done, JJ, I just stuck the answers in yesterday. PS The clue has 'deceased', not 'decreased'.

[JJ109]

Ha! I can't read my own writing! It got missed off the bottom of the page when I printed it, and so I wrote it on by hand!!! Thanks!

[ProfessorMaisie]

20d starts with v before it's replaced by the last letter of 'vaS[e]' - parasites/bloodsuckers.

[JJ109]

Many thanks once again ProfessorMaisie. All finished now!