In some fungus species a partial veil initially covers the pores or gills. As the fruit body expands and matures, the partial veil usually breaks to form a 'ring' on the stem. Suillus luteus usually has the remnants of the veil hanging on the upper quarter of the stem, while Suillus granulatus does not.
Freshly emerged Suillus luteus have a gelatinous coating, which explains its common name, Slippery Jack. S. luteus is mychorrhizal with various exotic conifers, meaning that it forms a symbiotic relationship with pines. Both Suillus luteus and Suillus granulatus were introduced to Australia from Europe with exotic trees.
Caps are convex at first, and very glutinous. They flatten as they mature, reaching a diameter of up to 150mm, and are viscid.
Pores are yellow, aging to a dirty yellow. A brown annulus forms on the upper portion of the stem, sometimes falling off leaving a purplish brown band or stain. The white or cream stipe is covered in fine brown speckles. Spore print is yellow-brown.