If you want to get picky, you could say that the Jack-in-the-pulpit is not a flower. It is an inflorescence that includes many flowers. The outer bract encloses the projecting structure called a spadix. Only at the base of the spadix can you see the true flowers. Here you see the female flowers, little green balls with white pollen collectors. Above them are a few male flowers, getting ready to release their pollen. Oops, no they're not! It turns out that Jacks may have only female flowers, only male ones, or both. If both, their function depends on the relative number of each. In an individual like the one here, the stamens will wither, and only the pistils function. In one with more stamens, the pistils wither. This insures cross pollination. Oops, no it doesn't! One study showed that the everage number of pollinating bugs to visit flowers was 1.5. Only an average of 30% of plants were pollinated. So fascinating Jack is very inefficient. But generations of wildflower watchers know he gets the job done.
Some Jacks are entirely green. At the other extreme they may have dark stripes on an almost white background. One factor in the difference may be habitat. I once transplanted some dramatically striped ones from a maple swamp to my garden. I'm sure that was a change to less acidity. In my garden they came up mostly green.