Cortinarius traganus, also known as Gassy webcap, has a convex to an umbonate, fleshy, silvery violet cap. It is mycorrhizal, usually with deciduous trees, but also found with conifers, often on acidic soil.

Cap initially spherical to convex, with the margin rolled inward, later flattened, sometimes with a large, broad, central umbo. The margin often cracks star-like, particularly in dry weather. Colour first pale azure violet to pale lilac colour, later fading to tan-brown or rusty brown. The surface is dry, silkily shiny or tomentose at the margin with membranaceous bronze fragments of the veil, it becomes later cracked into small scales. Gills sub-crowded, quite thick, broadly adnate, and often slightly emarginate. Colour slightly dirty violet when young, later brown. Stem tough and thick, bulbously at the base, and spongily stuffed inside. It is vivid violet for a long time in the upper part above the cortina, paler below, and covered with a tough, whitish, boot-like veil, which usually leaves upright zones on the stem. The cortina is violet. The flesh is saffron yellowish-brown to yellowish-brown except at the tip of the stem where it is dirty violaceous. Spore print rusty brown.

Microscopic Features:The spores are ellipsoid in shape, adorned with fine warts or dots, and have measurements of approximately 8-9 μm in length and 5-5.5 μm in width.

Cortinarius traganus on Wikipedia.