No, poems are typically not underlined.

Autumn leaves swirl and dance,
A symphony of gold and brown,
Nature's orchestra at its finest,
Bringing joy as they fall to the ground.

The rising sun in the east,
Embraces the sky with its warmth,
The world awakens to a new day,
And possibilities are reborn.

In the silence of the night,
Thoughts fill my mind like stars,
Each one shining bright,
As I marvel at life's infinite bars.

A heart in pieces, shattered and torn,
Slowly mending with each new dawn,
Love and hope guide the way,
Towards a brighter and better day.

Poems are usually not underlined but are italicized or placed in quotation marks depending on the publication's style.

Medium Poems

What happens to a dream deferred?
Does it dry up
like a raisin in the sun?
Or fester like a sore-
And then run?
Does it stink like rotten meat?
Or crust and sugar over-
Like a syrupy sweet?
Maybe it just sags
like a heavy load.
Or does it explode?

Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;

Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,

And both that morning equally lay
In leaves no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.

You may write me down in history
With your bitter, twisted lies,
You may trod me in the very dirt
But still, like dust, I'll rise.

Does my sassiness upset you?
Why are you beset with gloom?
'Cause I walk like I've got oil wells
Pumping in my living room.

Just like moons and like suns,
With the certainty of tides,
Just like hopes springing high,
Still, I'll rise.

Long Poems

Yes, the title of a poem is typically underlined or italicized. Here is an example of a long poem with a title:

Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;

Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,

And both that morning equally lay
In leaves no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way,
I doubted if I should ever come back.

-Robert Frost