 The basidia are 15 – 25 × 3 @.@ 5 – 5 @.@ 5 µm and have a slim , club @-@ like shape . Each <unk> features four sterigmata , each of which bear one spore . The spores ' shape is <unk> <unk> or cylindrical . Their surface is smooth and their walls are thin . Although they are <unk> and hyaline , the spores are amyloid , meaning they will turn bluish or purple when stained with Melzer 's reagent . This characteristic differs from other very similar species , and this gave the genus its name . 
