I just purchased a Jack-in-the-pulpit, Arisaema triphyllum, from a reputable store, Bordine's. The question I have is the spathe is green - it looks like the leaves of the plant. I bought this one, because it was the biggest one, and the salesperson assured me it would turn white/brown, which is the way I have seen them before. Well, I have had the plant a week and it is still as green as ever. Is this normal? Will it always be green or will it vary from year to year? Thanks!