Toxic mushrooms

Outline
• Outline & objectives
• Generalised description of mushrooms
• Edible mushrooms
• Mycetism
• The nasty one (Amanita phalloides)
• Mushrooms that grow on grass
• Mushrooms that grow on wood
• Identification

Objectives
• Provide an overview of what fungi and
mushrooms are
• Illustrate difficulties identifying mushrooms
• Give examples of toxic species that could be
found in NZ backyards
• Discuss information to collect for mushroom calls

Epidemiology
• In 85% to 95% of unintentional mushroom
ingestions the species is unidentified.
• Child exploratory ingestions are the most
common.
• Misidentification with edible
species is another significant
cause.
• Children and elderly at more
risk.
• Raw mushrooms are more
toxic than cooked.

Fungi
• Not plants
• Do not contain chlorophyll
• Use organic material from plants, animals and other
fungi as an energy source.
• Some live on dead organisms, some are parasites,
some are symbiotic with plants.
• Store glycogen (like animals) rather than starch as
plants do.
• Cell walls are composed of chitin – a complex
polysaccharide that cannot be digested by humans.
• Most fungi are microscopic (yeasts, moulds).

Mushrooms
• Mushrooms are the fruiting body (sporocarp) of
certain species of fungi.
• Main organism (the mycelium) consists of
hyphae (long, threadlike structures) forming a
web of tissue in the substrate.

Mushrooms
• Main function is to disperse spores.
• Fruiting occurs when environmental conditions
are favourable for spore dispersal and
germination.
• Unexpected weather patterns can alter fruiting
behaviour.

Mushroom Morphology
• Protective tissues cover the fruiting body during its
development
• In Amanita species, two veils of tissue occur:
o An outer enclosing bag, the universal veil
o An inner partial veil covering the developing gills

Ectomycorrhiza
• Symbiotic relationship between a fungus and the
roots of some woody plants
• Ectomycorrhizal fungi do not penetrate their
host’s cell walls. They form an intercellular lattice
of highly branched hyphae between epidermal
and cortical root cells.

Ectomycorrhiza
• Form a dense hyphal sheath surrounding the
root surface. Can be up to 40 µm thick, with
hyphae extending up to several cm into the
surrounding soil.
• Hyphal network aids in water and nutrient uptake
helping the host plant to survive adverse
conditions, fungal symbiont gains carbohydrates.
• Ectomycorrhizal fungi form on many temperate
forest trees, such as pines, oaks, willows,
Douglas firs, eucalypts, beeches and birches.

Edible mushrooms
• Agaricus bisporus (button / Portabello
mushroom)
• Agaricus campestris (field mushroom)
• Agaricus arvensis (horse mushroom)

Agaricus bisporus
• When immature and white, is known as the
button mushroom.
• When mature, known as portobello mushroom.
• Grows on manure,
compost, grass &
under conifers
(macrocarpa)
• All seasons except
mid-winter.

Agaricus campestris
• Field mushroom / meadow mushroom.
• Grows in arcs & rings on grass.
• Gills are pink both before & after caps open,
turning brown when caps are fully expanded.
• Never associated
with trees.
• Late summer to early
winter.

Agaricus arvensis
• Also known as Agaricus fissuratus
• Horse mushroom
• Gills are initially white, then become grey and
brown.
• Grows in arcs &
rings on grass.
• Late autumn to
early winter.

Mycetism
• Mycetism: poisoning caused by mushrooms
• Toxin levels can vary with:
o Season
o Geographical location,
o Soil type
o Elevation
o Age of mushroom
o Between parts of a single mushroom.
• Mycotoxicosis: poisoning caused by any fungal toxin
o E.g.; aflatoxins – toxins produced by moulds
o Some mycotoxins are valuable to humans, e.g.; antibiotics

Amanita phalloides
• When young the mushrooms look like a white ball just
at the soil surface. The top then splits and a white
mushroom grows out with the remains of the ball
forming a cup at the base.
• Gills are initially covered by a veil but this eventually
splits at the edge of the cap and leaves a ring towards
the top of the stalk.
• Young caps are off-white or greenish but at maturity
can range in colour from off white, light tan or greenish
• Caps are up to 12 cm diameter.

Amanita phalloides
• Most dangerous mushroom in New Zealand.
• Toxin concentration highest in the
annulus > gills > volva > cap > stalk 1
• Mature mushrooms are more toxic than
immature.
• One cap can kill an adult
• Forms ectomycorrhiza
with oak trees
• Spores are toxic,
wash hands

Cyclopeptides
• Polypeptide chains linked with a covalent bond to
create a ring structure.
• a-Amanitin is an inhibitor of RNA polymerase

Phalloides syndrome
• Latent asymptomatic phase (< 24 hours and usually up to 12
hours post-ingestion)
o No symptoms
• Gastrointestinal phase (6 to 24 hours post-ingestion)
o Abdominal pain, vomiting, severe diarrhea, hypovolemia, electrolyte disturbances, acid-
base disturbance
• Period of well-being (24 to 48 hours post-ingestion)
o Hepatic and renal function deteriorates
• Hepatic phase (3 to 5 days post-ingestion)
o LFT increases
o Acute hepatic failure
o Acute renal failure
• In fatal cases, death may occur 6 to 16 days following ingestion
due to hepatic and/or renal failure
• Time frames may vary considerably

Mushrooms on Grass
• Agaricus xanthoderma (yellow stainer)
• Clitocybe species
• Panaeolina foenisecii (haymaker’s mushroom)
• LBMs (little brown mushrooms)
• Note: mushrooms that feed on wood can occur
in grass that has woodchips or rotten wood
buried underneath it.

Agaricus xanthoderma
• Yellow stainer
• GI irritant
• GI effects may be due to phenol formed by
cooking
• Early onset gastric symptoms
• Serious toxicity unlikely

Agaricus xanthoderma
• Intense yellow forms when rubbed
• Caps up to 15 cm in diameter, with prominent
rings on the stalks.
• gills are white when young, becoming brownish
with age.
• Phenol smell

GI irritant syndrome
• Typically cause nausea, vomiting, diarrhoea,
abdominal pain.
• Symptoms usually occur within 30 minutes to 3
hours of ingestion and subside within 8 to 12
hours.
• Severe symptoms usually occur secondary to
significant fluid and electrolyte losses.

Clitocybe species
• Caps are white, off white, light brown, pastel
yellow, green, cream or pink.
• At maturity the caps become funnel-shaped and
the gills run down the stem.
• No ring on the stem.
• Found in pastures, woodlands and forests.
• Some are edible, others contain muscarine.

Clitocybe dealbata
• In fairy rings in grasslands and pastures in
summer and autumn.
• Usually found on grass such as lawns
• Can contain high
levels of muscarine.

Muscarine syndrome
• E.g., Clitocybe dealbata
• Symptoms are generally mild and short lived
• Rapid onset of symptoms
o Sweating, salivation, lacrimation, constricted pupils, blurred
vision, gastrointestinal upset, hypotension, pulmonary congestion
• Profuse sweating differentiates
muscarine poisoning from
general gastrointestinal irritant
mushrooms

Panaeolina foenisecii
• Cap 1 to 3 cm in diameter. Bell shaped when young
then becomes flat.
• Stalk 2.5 to 10cm long, 1.5 to 3cm thick
• Not highly toxic but have caused symptoms in children
• Haymaker’s mushroom
• Sometimes mistaken
for magic mushrooms
• Grow individually or in
small groups on lawns
and grassy areas

Hallucinogenic syndrome
• E.g., Panaeolina foenisecii
• Following ingestion symptoms usually develop rapidly.
• 10 to 30 minutes
o Anxiety, light-headedness, weakness, muscle aches, and abdominal discomfort
o Visual effects/hallucinations and perceptual distortions, sweating, facial flushing, and
incoordination
o symptoms intensify
• The symptoms usually wane and resolve after about 2 to 4
hours, before returning to normal
within 4 to 12 hours

Mushrooms on wood
• Galerina species
• Gymnophilus junonius (big laughing gym)
• Nemotoloma fasciculare (sulphur tuft)
• Pholiota squarrosa (scaly pholiota)
• Chlorophyllum rhacodes (shaggy parasol)
• Lepiota cristata
• Lepiota citrophylla (possibly fatal)

Galerina species
• Some species of Galerina contain dangerous
quantities of amatoxins.
• Generally have brownish, small caps up to 7cm
diameter
• Galerina unicolor
• Galerina marginata very toxic
• May be found in damp grassy or mossy areas.

Galerina marginata
• Cap 1.5 to 4cm diameter
• Contains a-amanitins in sufficient quantities to
cause death.
• Grows on decaying wood, this may be under
grass or moss.
• See cyclopeptide syndrome slide

Gymnophilus junonius
• Big laughing gym
• Found in late summer and early autumn in clusters on
stumps and on soil containing rotting wood.
• Caps are up to 18 cm in diameter and the brown gills are
often covered with a dusting of rusty brown spores. There
may be a ragged ring on the stalk or merely a darker zone.
• The smell is not unpleasant but it has a very bitter taste and
content.
• Consumption can result in uncontrollable
laughter, nausea, abdominal pain and
convulsions (Hallucinogenic syndrome).
• Has been found growing on wood chips
in the grounds of a play centre.

Nemotoloma fasciculare
• Aka: Hypholoma fasciculare
• Sulphur tuft
• Found throughout the year in clusters on stumps
of trees or logs.
• About 10 cm high and up to 8 cm across
• when young have sulphur yellow caps and gills.

Nemotoloma fasciculare
• Bitter taste
• The symptoms of poisoning begin up to 10 hours
after eating and include nausea, vomiting,
abdominal pain and in some cases death.
• May cause symptoms
similar to cyclopeptide
syndrome

Pholiota squarrosa
• Scaly Pholiota
• Found in summer to late autumn at the bases of
trees, on rotting stumps or logs, on burnt ground
or occasionally on living trees.
• Yellowish to light brown to brown caps can be up
to 12 cm in diameter and either very gelatinous
or scaly.
• GI irritant syndrome

Chlorophyllum rhacodes
• Shaggy parasol
• Caps up to 15 cm diameter
• Stem can be up to 30 cm high and 4 cm diameter.
• Light coloured at the top, light brown towards the base.
• Caps covered in chestnut coloured scales.
• Gills are initially white but turn light brown with age.
• Often found in the litter under macrocarpa.
• Can be edible but also causes GI irritant
syndrome

Lepiota cristata
• Lepiota are found growing on decaying woody material
in forests, open areas, pasture and even compost
heaps.
• Caps range from a few cm to 10 cm in diameter and
many are ornamented with rings of scales.
• Cap is white/cream with reddish-brown scales. The
centre is darker than the rest of the cap.
• Toxicity unknown
(suspect)

Lepiota citrophylla
• Found in New Zealand
• Poisonous, possibly deadly. The poisons are
cyclopeptides similar to Amanita phalloides.
• Cap: 1.5 to 5cm diameter. Brown centre with
yellow edges.
• Gills are sulphur yellow
• Pale yellow stalk
• Commonly found in greenhouses
• (no images online)

Identification
considerations
• Refrigeration can alter the structure of the
mushroom
• Moisture makes identification more difficult and
hastens decomposition
• Don’t store in plastic bags

Calls from
patient/caregiver
• Send the patient to hospital or medical centre for activated
charcoal (if within 12 hours of ingestion)
• They should take a sample of the mushroom (preferably
several, whole) with them (in a paper bag, in an airtight
container)
o (They may also need to take their own camera and cords, if they have one)
• Record accurate details on the callsheet of:
o mushroom description,
o where it was growing,
o if it was near a tree(s) and what type of tree
o if it was near other mushrooms
• Inform the patient
o that they need to receive charcoal (if appropriate)
o that the medical staff can call the NPC to have the mushroom identified if
they wish

Calls from doctors
• Inform them that they have the option of sending a photo to the
NPC if they wish.
o The aim of identification is to exclude Amanita phalloides
o If they decide to send an image through, ask them to email the picture to your own
email address.
o Ensure you record accurate details on the callsheet of mushroom description, where it
was growing, if it was near a tree/s or other mushrooms
• Mushroom description
o Size
o Shape
o Colour (cap, gills, stem)
• Where it was growing
o Region in the country
o Field, forest, lawn
o On something else (log, tree)
• Surrounding features
o Growing on, or near trees
o Were there other mushrooms around? the same type or different?

Mushroom photos
• Take photos of:
o Any remaining parts of the actual mushroom ingested.
o Several whole mushrooms from the same area.
• How to photograph:
o Place the mushroom on a white background
o Adjacent to a ruler
o Take close-up photos with good lighting.
o The mushroom should take up most of the photo.
o Photos should be taken from a variety of different angles.
• What parts to photograph:
o Whole mushroom
o Cap
o Gills (underside of cap)
o Stalk (particularly bottom of the stalk)
o If it is a puffball, photograph it whole and also photograph it cut in half

High Risk
• White mushroom with white spores under oak trees
(Amanita phalloides)
• Ingestion of raw mushrooms
• Children and elderly
• Annulus (ring on stem)
• Swollen or bulbous base
• Puffballs could be immature Amanita or Scleroderma
• Warts or scales on the cap
• Blue staining when a mushroom is bruised

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