This is what I get from your dream. The old man is that ancient part of you with all it's wisdom. He's like a shaman and you trust him. This is good that you trust yourself. Hands do have energy and the plant growing out of yours I suspect used part of the energy, but also releases some of it. Purple is associated with intuition, White with Spirituality. I'm wondering which palm was involved. If the right, this dream would indicate a future time. The left would mean the past, and may be a way of reminding you of lessons learned in the past. Otherwise I'd say this dream is pointing you toward a more spiritual base. That's my thoughts.
Marj

In my dream, a strange and dirty/hobo

RACIST/PREJUDICED

looking man with cloudy but intense eyes

LIVER FLUSH

was holding my hand in his,

HOMOSEXUAL

with my palm open and facing up.

YOGA

He was whispering to himself and I couldn't make out what he was saying,

EAR DRUM FLUSH

and was placing things like dirt and seashells

RACIST

in my hand. Although he was crazy looking I felt at ease and trusted him.

POOR JUDGEMENT

Suddenly I felt an excruciating pain

RESULT OF POOR JUDGEMENT

in the centre of my palm, and began to scream at the top of my lungs.

RESULT OF POOR JUDGEMENT

Out if the mound of dirt, suddenly a plant began to sprout, and I could feel energy pouring from my hand, as the plant continued to grow to about 3 feet while the whole time I am screaming because the feeling is so intense.

SCHIZOPHRENIA

Yet I do not try to stop it.

SCHIZOPHRENIA

The pain stops. I stop screaming and I am left with this large plant with purple and white flowers.

MAYBE YOU NEED TO TAKE SOME PSYCHEDELICS?