Retlaw plant

From Memory Alpha, the free Star Trek reference

The retlaw plant is a poisonous, mobile plant native to the planet Phylos. The retlaw moves by walking on its roots. When it stops, its roots bore back into the ground.

In 2269, Hikaru Sulu was poisoned by the retlaw and nearly died before antidote was given to him by Agmar. (TAS: "The Infinite Vulcan")

Retlaw backwards is Walter. Walter Koenig penned the episode.