Hypsizygus ulmarius? Published December 13, 2016 at 519 × 423 in The Great Elm Oyster (Hypsizygus ulmarius) Mix-up No less that Paul Stamets has touted the H ulmarius on his site and trademarked the name Hypsizygus ulmarius Garden Patch (HUG) which depicts a Pleurotus-like oyster.