Thanks Anna! If I understand your question, the "palms" I wrote about are actually the leaves of the ginger plant after it sprouts. The ginger root in the grocery will be clearly marked as ginger. It's the nubby looking whitish roots. Hope I didn't make that more confusing.
I did have to do some research on the botanical names of some of those more exotic tubers. Most was done on my cell phone while waiting for DH who was having a battery of tests run last month!
Christine, sushi ginger sounds really interesting! Can you share the recipe with us? Bet it would be good in other dishes too.