Wyman later stressed the importance of "White Tulip" in the show's evolution, calling it a "mythalone" because its elements were designed to create the ideal episode to satisfy both new and hardcore viewers.

As he contemplates the final letter, he and the rest of the Fringe team are called to investigate several dead bodies in the passenger car of a train.

Walter, after being told the victims' personal electronics were drained of power, suspects someone drew energy from both the people and their devices' batteries.

Alistair reappears on the train at the same point in time as his previous travel, again having drained the people aboard it, and alters his behavior to avoid another encounter with the Fringe team.

Walter tells Alistair how to correct the mistake that caused him to jump to the train but warns him of the other consequences that changing events will bring, explaining that stealing Peter from the parallel universe has left him wracked with regret.

Despite being a man of science, Walter's torment over the years drove him to believe in a higher power, and he hopes for a sign of God's forgiveness—and thus, eventually, Peter's—in the form of a white tulip.

Alistair jumps back in time again by only a few hours to complete the modified power calculations based on Walter's comments, and to prepare a pre-addressed letter he brings with him.

In the present, the events of the episode never occurred, and Walter, having time to contemplate the letter to Peter instead of being called to the case, tosses it into the fireplace.

[8] In a later Twitter post, Wyman dismissed speculation and confirmed that Weller's character Alistair Peck did indeed die at the end of the episode.

Ken Tucker from Entertainment Weekly enjoyed the episode, writing "Fringe is becoming ever more adroit at blending its mythology with its paranormal cases".

[16] After initially expecting a "filler" episode, Ramsey Isler of IGN said he was "pleasantly proven wrong", as the "story turned out to be one of the best of the series".

[19] New York Magazine's Tim Grierson loved all the interactions between Noble and Weller, and thought they were so "compelling together that they helped justify an episode that could have very easily been terribly hokey — instead, it was one of the season’s best standalone stories".

The tulip of the title represents forgiveness — faith in love — and became within the series a semi-recurring symbol of fragile hope, and, to the show's audience, a cynosure of the devotion of Fringe fandom.

"[25] IGN ranked it as the second best, explaining that "despite a few technical flaws with special effects and a little under-utilization of Weller in the first half, the veteran cast delivers an excellent script with skill.

Executive producer J. H. Wyman later commented in an interview that "the 'White Tulip' stuff is all connected thematically because that was the episode where Walter believes in God," and further explained that these themes would return again in the season three finale.

Wyman and Jeff Vlaming submitted "White Tulip" for consideration in the Outstanding Writing for a Drama Series category,[31] but failed to garner a nomination.