Phelch was a member of an ancient race of sentient vegetables. Overcoming the limits of their roots, the vegetables evolved into space-spanning overachievers. Unfortunately, they met their doom when in their vanity, they failed to pick themselves at the first cosmic frost. Phelch, in the form of a turnip, was the sole survivor and wandered the trackless void of space for eons, searching for a more efficient body to frame its superior intellect and incomparable power. Phelch eventually crash-landed on Earth, where, although the bulk of it was burnt up in the atmosphere, it encountered Arthur Winslow.
Arthur Winslow was a would-be author who dreamed of living the life of a fictional hero, along the lines of the Lone Ranger, the Green Hornet, James Bond, or Buck Rogers. His fictional stories of that genre were rejected, because they were out of fashion. Instead he was forced to become a security guard to pay his bills. He spent seven uneventful months in that position before encountering Phelch, having freshly crash-landed on Earth.
Phelch convinced Winslow to allow a merger, enabling him to become the super-hero he'd always wanted to be. As Turnip-Man he saved the lives of a busload of people whose bus had driven off of a bridge as a result of a scuffle between Howard the Duck and the Kidney Lady.
When Winslow's friend and roommate, Beverly Switzler recognized him, Phelch took over their combined form in order to experience physical pleasure. The Space Turnip grabbed Beverly and took her to Sunset Slope. Howard, following advice from the Kidney Lady, tracked them and confronted the Space Turnip in battle. Howard, figuring "the brains are in the greens," tore the leaves and stem from Turnip-Man. The Space Turnip pulled Howard high into the air planning to drop and crush him, but Howard succeeded in maneuvering it too close to a smokestack, where it was destroyed. Arthur was left none the worse for wear, and apparently powerless.
Later, during a confrontation between Howard, the Kidney Lady, and a cab driver, Arthur was present and had a passing moment of deja vu, but nothing came of it.