This plant will last for several years as a cluster of basal leaves. I know from experience that Columbo can frustrate a beginning botanizer. I walked past the same cluster plants for two years before one decided to flower.
When all requirements of the plant are met, a thick stalk will ascend 4 to 6 feet and clusters of green blooms will appear. Although they are quite showy when viewed up close, they quickly blend into the dappled sunlight of the woods and can be hard to notice at a distance.
Most years, only a few flowering plants are seen at one site. There are at least a dozen plants showing in the photo above. Scenes like this remind me of the man-eating plants in the old Tarzan movies or John Wyndham's Triffids. I can imagine that lead plant leaning forward to unleash its sting upon me.
Just one more thing. Deer Flies are out in big numbers so be ready to employ whatever defense tactics you usually use. Any guesses on how many pictures you can take before a Deer Fly drills completely through the back of your hand?