Is the comma after poem mandatory?

No punctuation, grammer usage, or even spelling is mandatory. Language is a living thing, and the best folks can do is try to describe what people are actually doing, and try to provide a framework for what they think people should be doing.

But here's what I think is a good guide on what you're asking.

http://classroom.synonym.com/place-comma-before-poems-title-sentence-3778.html

In this case, you could not lift "The Giving Tree" out of your sentence and still have the sentence make sense, so you would not use a comma.

Just italicize the title.

How would that affect comma usage, though, which is the topic of the thread?

In any case Tang, I'd change third "the" to "a"

Poetry is any old bollux that a publisher can profit from.
I have verses published worldwide, and they're all self-relative crap.
GRAMMAR MATTERS NOT IF IT SUPERCEDES REWARD.

Shouldn't it be supersedes?

No.
It can be 'soopaseeds' for all the 'profiteers' care.

ps. Nothing's gonna change my world.

Atu, Lennon:)

NO???

In the same way that your 'No???' does not require three questiomarks.
What's that about????????????

It doesnlt matter if the language you use, or the grammatic limitations you affix to it, is/are tolerable or not.
All that matters is WHERE IT COMES FROM, not where it's headed.

NO?