 <unk> saliceticola produces mushrooms with caps of between 7 and 40 millimetres ( 0 @.@ 28 and 1 @.@ 57 in ) in diameter . The shape of the cap varies , depending on the age of the mushroom . In younger specimens , they are conical or nearly so , but as the mushroom matures , the caps flatten into a more convex or flat shape . As such , the height of the cap varies from 4 to 11 millimetres ( 0 @.@ 16 to 0 @.@ 43 in ) . The cap features an umbo that is usually very prominent . Around the umbo , the cap surface is smooth , but towards the cap margin , the surface is defined by fibrils running from the margin towards the umbo . The cap sometimes splits along these . The cap 's colour varies from yellow @-@ brown to pale brown , and is palest at the margins . The umbo contrasts to this somewhat , being a grey @-@ brown or red @-@ brown . The slender stem measures from 0 @.@ 7 to 6 @.@ 2 centimetres ( 0 @.@ 3 to 2 @.@ 4 in ) long by 1 @.@ 5 to 6 @.@ 5 millimetres ( 0 @.@ 059 to 0 @.@ 256 in ) thick . It thickens slightly towards the base , where it joins a large , well @-@ defined " bulb " that can be up to 11 millimetres ( 0 @.@ 43 in ) across . Shallow grooves run up the surface of the stem , which is covered in a fine white powder . In one case , however , an atypical specimen was recovered with an almost completely smooth stem , free of striations or powder . The stem varies in colour , with whitish , pale yellow @-@ brown , pale red @-@ brown , pale brown and grey @-@ brown all observed , while the base is white . No veil or ring is visible . 
