Buttercup (Suillus) is a genus of basidiomycote fungi of the Suillaceae family. It got its name because of the oiliness, the slippery to the touch hairpins. Characteristic features that distinguish other types of buttercups from other boletus are the sticky cap. The cap is 3-8(10-12) cm in diameter, hemispherical, then convex or flattened, with a blunt edge, chestnut or yellowish-brown, glabrous, sticky. The skin is removed very easily. Pores are whitish at first, turn yellow with age, angular-rounded. Spores are dirty-yellowish, 7-10.5 × 3-3.5 μm. Leg 3-8(10) × 1-3 cm, dense, whitish, later yellowish, brownish, with a ring that quickly disappears. The ring is plate-membranous, white, later brownish, sometimes with a purple tint. The pulp is watery, whitish, yellowish with age, darker under the skin, does not change when cut in the wind, the taste and smell are pleasant.