Yellow Fieldcap Mushrooms

Bolbitius titans

We had several big trees taken down this spring and consequently we’ve been blessed with two enormous mulch piles in the yard. It was inevitable that a few mushrooms were soon to follow.

I was amazed by watching this species of mushroom come and go in the mulch.  One day I would see a few bright yellow mushroom “buds” coming up, and the next day I’d see a stand of gangly beige parasols in various stages of decomposition. This happened multiple times during a period of frequent rains. It was as though the mushrooms came up, opened, and deliquesced in less than 24 hours… Could that be?

The flat caps have a yellowish center and striations along the margin

From my reading, it turns out that a rapid fruiting cycle is one of the characteristics of yellow fieldcap mushrooms. These mushrooms start out as bright yellow, oval fruiting bodies that are noticeably wet. In a few hours the pale-colored stipes grow tall and the caps flatten out and begin to fade in color. For a short while there are striations along the margin of the cap and the center of the cap is yellow or yellowish-brown. Within a few more hours, the gills turn from pale yellow to dark brown, eventually producing brown spores before the mushroom falls to the ground. All this in less than a day!

In addition to growing on mulch, yellow fieldcaps are often found growing in the grass in urban areas or in pastures in agricultural areas. They can first appear in late spring and then throughout the summer, usually after a rain.

Also known as “Egg Yolk Fungus”, some folks think this mushroom looks like a fried egg on a stick. I think that’s a stretch, but it IS an interesting name!


2 Comments Add yours

  1. These must be really fascinating to watch throughout their various stages. Are the gills on top rather than the bottoms? I don’t recall seeing any wild mushrooms quite like these in the Deep South where I’m from.

  2. Dianna J says:

    Great photos!

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