 In deposit , the spores are cinnamon @-@ colored . Viewed with a microscope , they are pale yellow , smooth , and roughly elliptical in shape , and measure 8 – 9 @.@ 5 by 3 @.@ 5 – 5 µm . The basidia , the spore @-@ bearing cells , are club @-@ shaped and 4 @-@ spored , with dimensions of 21 – 25 by 5 @.@ 5 to 6 µm . The pleurocystidia ( cystidia found on the sides of a gill ) range in shape from cylindrical to club @-@ shaped and are arranged in bundles . Both the bases of the bundles and the surface of the cystidia may be covered with brown pigment particles . Cheilocystidia are cystidia located in the gill faces . In S. americanus , they are mostly club @-@ shaped , often with an expanded apex , and like the pleurocystidia , are arranged in bundles , with brown pigment particles at the base of the bundles . Bundles of cystidia near the tube openings may sometimes be visible with a hand lens . Like all Suillus species , the cystidia of S. americanus will turn orange @-@ brown in the presence of a solution of 3 % potassium hydroxide . The slimy layer on the cap surface results from an interwoven layer of gelatinous hyphae that are typically 3 – 5 µm thick . 
