Lepiota s.l.

The fruit bodies are mushrooms that arise from soil or humus. The caps of mature specimens are dry and typically with a whitish base over which (except towards the centre) there are concentric rings of scales, usually of a different colour, commonly brown. The centre of the cap l is of the same colour as the scales.

In young mushrooms, before the cap has expanded, the cap is uniformly of the same colour as the scales. However, as the cap expands, the cells that make up the skin of the cap do not expand (whereas those in the flesh of the cap do). That skin ruptures. As the cap enlarges, the greatest expansion is at the margin, the least at the centre. Hence, the skin suffers its greatest breakage at the margin, resulting in a very sparse ring of scales at the margin. There is less and less breakage as you move inwards so the scale density increases as you move inward and at the centre, where there is  very little or no expansion, the colour is solid because there the skin remains largely intact.

The gills are white and no gills reach the stem (technically, the gills are free). In most mushroom genera, if you look at the underside of the cap you will see a mix of long and short gills extending inwards from the cap edge with long gills reaching the stem. There are only a few mushroom genera with free gills.      

Usually, on the stem there is a ring of tissue. This is the remnant of the partial veil, a membrane that covered the gills when the mushroom was still quite immature. At that time the membrane extends from the cap margin to the stem. As the cap expands the partial veil breaks at the cap margin and remains attached to the stem. However, in some species this ring is fragile and may break up and fall off.   

The pair of letters s.l. is a standard abbreviation in botanical works for the Latin phrase sensu lato (meaning 'in the broad sense'). Lepiota, as understood decades ago, has been split into several genera that are not always easy to recognize visually. Note that the genus Lepiota still exists but more narrowly defined than before. The usage of s.l. will, at times, allow a level of identification finer than family but where it is not possible to have any confidence in assigning a genus to a photograph.