Mr Patterson was working on a contract to catalogue biodiversity amongst plants, birds, mammals, lichens and invertebrates for the university.
Speaking in an interview on BBC Radio Scotland, the ecologist said that he had a "quirky theory" that soldiers' boots may have picked up spores while tramping the fields of Flanders during the Great War.
During World War One the Napier university campus site served as a military hospital where the renowned war poets Wilfred Owen and Siegfried Sassoon were famously treated.
Mr Patterson said: "Looking at an old photograph of First World War officers standing on the grass banking where I found the fungi, my thoughts turned to the question of how the species arrived here at all.”
"I thought of the soldiers' boots trampling the devastated fields of Flanders and perhaps picking up spores of C cinereoides and then depositing them on that grassy bank below the old Hydropathic."
However, Mr Patterson added that his theory his theory was not backed up by scientific evidence.
Head of the university contract, Jamie Pearson, said: "This discovery was most unexpected.”
"The fungus has now been accepted and entered into the records as a first for Scotland and the specimen is now with the Royal Edinburgh Botanic Garden Herbarium and is the only specimen they have of this species."
As it is Sunday here is probably Wilfred Owen’s most famous poem.
Dulce et decorum est
Bent double, like old beggars under sacks,
Knock-kneed, coughing like hags, we cursed through sludge,
Till on the haunting flares we turned our backs
And towards our distant rest began to trudge.
Men marched asleep. Many had lost their boots
But limped on, blood-shod. All went lame; all blind;
Drunk with fatigue; deaf even to the hoots
Of gas-shells dropping softly behind.
Gas! GAS! Quick, boys!—An ecstasy of fumbling
Fitting the clumsy helmets just in time,
But someone still was yelling out and stumbling
And flound'ring like a man in fire or lime.—
Dim, through the misty panes and thick green light,
As under a green sea, I saw him drowning.
In all my dreams before my helpless sight
He plunges at me, guttering, choking, drowning.
If in some smothering dreams you too could pace
Behind the wagon that we flung him in,
And watch the white eyes writhing in his face,
His hanging face, like a devil's sick of sin,
If you could hear, at every jolt, the blood
Come gargling from the froth-corrupted lungs,
Bitter as the cud
Of vile, incurable sores on innocent tongues,—
My friend, you would not tell with such high zest
To children ardent for some desperate glory,
The old Lie: Dulce et decorum est
Pro patria mori.