Various gingers have escaped captivity in the islands and become quite invasive, crowding out native plant species. Much effort is put into control.

^ I have heard that from a Maui floral book..

my question still remains, is it the medicinal / cooking type

Wild ginger and edible ginger are different. Not that you couldn't try eating it. fyi--there are many types of ginger. including the wild yellow and white and shampoo which grow wild in Hawaii. There is also a type that they pickle the flower heads that grow out of the ground from the rhizome. I once had it, but I lost it unfortunately. The flowers on commercial ginger are not at all like those of the wild ones. There is also a cultivated 'blue' ginger, which is also grown for its flowers not as food.

question...has anyone been able to root the wild ginger in water??

Habeeb, what you are seeing is probably the floral type of ginger, not the edible type. The edible type is short and has a thin stalk, floral type is usually tall with a robust stalk. Also flowers from the floral type will be at the top of a stalk, where the flowers of the edible type come out of the ground on a short stalk and is in the shape of a bulb, pretty much like the shampoo ginger.