Wednesday, May 19, 2010

Little brown mushroom (LBM)

It's been raining for the last two or three days here in Rockville and the soil is quite humid. Walking to work today I found a large number of little brown mushrooms growing on the lawn around the sidewalks (Woohoo!). They were very fragile and in the morning they looked like as having a dark brown ring towards the border of the pileus (cap). I took some photos and collected some specimens to have a look later. I kept some in my jacket's pocket and I carried one in my hand, just in case. The one I carried on my hand changed color and became a darker brown, specifically on the region where I was holding it. Below are my notes on these little ones:

Date: 05/18/2010

Location: Rockville, MD

Growing on grass in groups of 5-10 individuals (gregarious) near the sidewalk.

Stipe length - 6.0 cm
Stipe diameter - 2 mm
Pileus height - 1.5 cm
Pileus diameter - 2.0 cm

Pileus - Conical, glabrous (bald), soft, light brown with darker edge (bicolorous) when fresh but single colored (light brown/grey) after loosing humidity. Hymenium is gilled and cinnamon cinnamon brown color. Lamella are free and well spaced, lamelulla are present near the edge but do not continue for more than a few millimiters. Border is entire. Smell is non-distinctive (I did not taste it ;-).
Stipe - Centrally attached, light brown/silverish, hollow, fibrous (when cut apart separates in thin strings),  straight and equal, no ring, volva or anulus observed. Inserted.
Spore print - purple/brown
Spores - dark yellow under the microscope, elliptical and with a apical germ pore (at 400x)

This is most probably a specimen of Panaeolus foenisecii (Pers.) J. Schrot,. also known as Lawn Mower's Mushroom. This mushroom is a common urban inhabitant that grows in lawns, specially after rain, and it does not last more than one day. It is possibly poisonous and according to some may contain low levels of hallucinogenic compounds (psilocybin and psilocin). As a curiosity, according to Roody's Mushrooms of West Virginia and the Central Appalachians, foenisecii is derived from the latin word meaning "mower" or "harvester".

All Panaeolus have conic to campanulate pileus, thin stipe and generate purple-brown spores (sincerely I can't see where is the purple) with apical germ pore.  They usually grow on grass or dung.

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