An unexplored jungle world where a thorny plant infects Commander Riker with a deadly microbe in Shades of Gray, the closing episode of The Next Generation's second season.
Surata IV is a swampy, overgrown planet surveyed by the Enterprise-D in 2365. It appears briefly in Shades of Gray.
During a survey, Riker is pricked in the leg by something he does not see. Pulaski finds an organism, part bacterium and part virus, spreading along his nervous system towards his brain. Data and La Forge return to the surface and identify the source as a vine with thorns that strikes at passing warm-blooded creatures.
Riker falls into a coma. Pulaski discovers that the microbe is driven back by the brain chemistry of unpleasant feelings, so she stimulates his memories of fear, grief and anger until the infection is destroyed.