In “The Day of The Triffids,” the author details an inscrutable menace and a central conflict made worse by human greed and bickering. There is also a firm determination on the part of the author to not explicitly detail the origin of the threat faced by the protagonists. The author never really tells the reader where the Triffids came from, but we can assume they were created by the scientist desire to create a usable plant, and something goes very wrong. A mutation in the plant creates a monster that man can no longer control.
"For years, humans have been cultivating a mysterious species of plant called the triffid because the oil and juice extracted from the plant make excellent cattle feed and are profitable for business. The origins of the seven-foot-high triffids are obscure, but the plant appears to have been the result of human biological experimentation."