Fungal Glossary for Indoor Environmental Testing

This glossary serves as a reference guide for understanding fungi and particles commonly detected during mold and IAQ assessments. It is organized into four categories—Indoor Water-Related, Indoor/Outdoor, Predominantly Outdoor, and Particulates—to help clarify where each is typically found and what it may indicate. It provides educational guidance only and is not a diagnostic tool or a substitute for professional inspection or laboratory testing.

Predominantly Indoor Water-Related Fungi

These fungi are NOT typically abundant in outdoor air, and their detection indoors often indicates water damage or chronic moisture. Even low quantities may be significant.

Aspergillus/Penicillium Chains

• Common Name: A/P Chains

• Scientific: Aspergillus spp. / Penicillium spp.

• Natural Habitat: Soil, decaying vegetation, stored foods

• Indoor Substrates: Wet drywall, insulation, dust, wood, food sources

• Water Activity: Moderate–high moisture

• Spread: Airborne conidia, easily aerosolized

• Allergen Potential: High; respiratory sensitizer

• Toxins: Some species produce mycotoxins & VOCs

• Comments: Chains indicate active indoor growth nearby — outdoor spores typically appear single, not chained.

Chaetomium

• Common Name: Chaetomium

• Scientific Name: Chaetomium globosum (most known)

• Natural Habitat: Cellulose-rich, chronically damp environments

• Indoor Substrates: Wet drywall, paper, wallpaper backing, wood framing

• Water Activity: Requires very wet conditions

• Spread: Ascospores via water disturbance or structural damage

• Allergen Potential: Moderate; associated with respiratory irritation

• Toxins: Some species produce chaetoglobosins (mycotoxins)

• Notes: Strong indicator of long-term water intrusion.

Clado-Sphaerospermum

• Common Name: Clado-Sphaero

• Scientific: Cladosporium sphaerospermum

• Natural Habitat: Vegetation, humid indoor surfaces

• Indoor Substrates: Window sills, HVAC, wet drywall, wood

• Water Activity: Needs more moisture than typical Cladosporium

• Spread: Air currents; surface sporulation

• Allergen Risk: Moderate–high

• Toxins: Rare / low known toxicity

• Comments: Reliable moisture indicator & visually identifiable.

Fusarium

• Common Name: Fusarium

• Scientific: Fusarium spp.

• Natural Habitat: Plants, soil, agricultural settings

• Indoor Substrates: Very wet drywall, humidifiers, potted plants, produce

• Water Activity: Very high — thrives in saturated conditions

• Spread: Airborne spores, water splash, contaminated produce

• Allergen Risk: Potential irritant; can infect immunocompromised

• Toxins: May produce trichothecenes, fumonisins, zearalenone

• Comments: More common outdoors, but presence indoors implies persistent wetness.

Gliomastix

• Common Name: Gliomastix

• Scientific: Gliomastix spp.

• Natural Habitat: Soil, decaying vegetation

• Indoor Substrates: Occasionally on water-damaged building material

• Water Activity: High moisture requirement

• Spread: Fragmentation & conidia release

• Allergen Risk: Unclear

• Toxins: Unknown

• Comments: Uncommon, but notable when present indoors.

Scopulariopsis

• Common Name: Scopulariopsis

• Scientific: Scopulariopsis brevicaulis (frequent species)

• Natural Habitat: Soil, decaying organic matter

• Indoor Substrates: Damp wood, drywall, subflooring

• Water Activity: Comparable to Stachybotrys (high)

• Spread: Spores release upon drying/disruption

• Allergen Risk: Respiratory/allergic concern

• Toxins: Potential metabolites; less documented

• Comments: Presence indicates severe moisture, often co-occurs with Stachybotrys.

Stachybotrys

• Common Name: Stachy / “Toxic Black Mold” (informal)

• Scientific: Stachybotrys chartarum

• Natural Habitat: Cellulose materials with chronic saturation

• Indoor Substrates: Wet drywall, OSB, insulation, paper materials

• Water Activity: >0.95 aw — requires continued water source

• Spread: Heavy sticky spores — not easily airborne unless disturbed

• Allergen Risk: Sensitizer; potentially inflammatory

• Toxins: Trichothecenes possible in some strains

• Comments: Detection indoors strongly signals long-term water damage; difficult to capture with air sampling.

Ulocladium

• Scientific: Ulocladium spp.

• Natural Habitat: Outdoor vegetation, soil

• Indoor Substrates: Wet gypsum board, carpets, wallpaper

• Water Activity: High moisture

• Spread: Airborne spores when dried

• Allergen Risk: Major allergen

• Toxins: None strongly documented

• Comments: Can resemble Alternaria microscopically.

Wallemia

• Scientific: Wallemia sebi (most common)

• Natural Habitat: Dry food, dust, low-moisture environments

• Indoor Substrates: House dust, wooden surfaces, insulation

• Water Activity: Extremely low (xerophilic)

• Spread: Easily aerosolized

• Allergen Risk: Sensitizer for some individuals

• Toxins: May produce walleminol & wallimidione

• Notes: Rare in nature but persistent in dry indoor spaces — opposite profile of Stachybotrys.

Indoor/Outdoor Fungi

These fungi are common outdoors and may appear indoors through air exchange or as settled dust. Indoor presence does not automatically indicate mold growth or water damage. Interpretation depends on quantity, comparison to outdoor control, and building conditions.

Alternaria-like

• Common Name: Alternaria

• Scientific Name: Alternaria spp.

• Natural Habitat: Decaying vegetation, soil, plant surfaces

• Indoor Substrates: Damp drywall, carpeting, window sills

• Water Activity: Moderate–high moisture

• Dissemination: Airborne spores; large multicelled conidia spread easily outdoors

• Allergen Potential: High — asthma/exacerbation documented

• Toxins: Some species produce alternariol, tenuazonic acid

• Comments: Typically outdoor; elevated indoors suggests moisture.

Aspergillus / Penicillium (General Group)

• Scientific Name: Aspergillus spp. / Penicillium spp.

• Natural Habitat: Soil, vegetation, stored foods, global ubiquity

• Indoor Substrates: Dust, drywall, insulation, carpeting, food storage

• Water Activity: Grows even with lower humidity, thrives more when wet

• Spread: Highly airborne conidia — fast colonizers

• Allergen Potential: High — known sensitizers

• Toxins: Some species produce mycotoxins & VOCs

• Comments: Common in homes. High indoor levels vs outdoor = possible indoor growth.

Cladosporium

• Scientific Name: Cladosporium spp.

• Natural Habitat: Plants, wood, soil — extremely common outdoors

• Indoor Substrates: Windows, HVAC, cold surfaces, wood trim, dust

• Water Activity: Moderate moisture needed for growth

• Spread: Airborne dry spores; abundant seasonally

• Allergen Potential: Very high — common trigger for allergies

• Toxins: Rare/low concern

• Comments: Can appear indoors in large numbers; elevated vs outdoor = growth source.

Predominantly Outdoor Fungi

These species are primarily outdoor molds. Their spores frequently enter homes through ventilation, doors, windows, or human/animal transport. Indoor detection is normally not a concern unless levels are significantly higher indoors than outdoors, which may indicate unusual infiltration or vegetation/soil disturbance inside but unlikely to grow indoors.

Arthrinium

• Scientific Name: Arthrinium spp.

• Habitat: Wood, grasses, plant debris

• Indoor Substrates: Rare; occasionally damp cellulose

• Water Needs: Moisture-dependent

• Dissemination: Wind-borne spores

• Allergen Risk: Moderate

• Toxins: Some species associated with mycotoxin production

• Notes: Mainly outdoor; indoor presence linked to plant soil or water damage.

Ascospore (Group)

• Scientific: Ascomycota spore group

• Habitat: Fungi on plants, soil, decaying matter

• Indoor Substrates: Rare active growth

• Water Needs: Varies widely

• Spread: Wind, storm activity, seasonal bloom

• Allergen Risk: Low–moderate

• Toxins: Not typically relevant

• Notes: Common outdoors; appear heavily after rain. Indoors usually indicates air exchange, not growth.

Basidiospore

• Scientific: Basidiomycota spore group

• Habitat: Mushrooms, bracket fungi, yard mulch

• Indoor Growth: Almost never grows indoors

• Water Needs: Not applicable indoors

• Spread: Massive airborne release during humidity cycles

• Allergen Risk: High potential

• Toxins: Not a common toxin concern

• Notes: High indoors suggests poor filtration or ventilation, not mold infestation.

Bipolaris

• Scientific: Bipolaris spp.

• Habitat: Soil, grasses, crops

• Indoor Substrates: Rare; fabrics when wet

• Water Needs: Moisture

• Dissemination: Airborne

• Allergy: A known asthma trigger

• Toxins: Some strains produce mycotoxins

• Notes: High indoors = outdoor penetration or plant contamination.

Bispora

• Scientific: Bispora spp.

• Habitat: Soil, wood

• Indoor Substrates: Occasionally damp lumber

• Water Needs: High

• Allergen Risk: Unknown

• Toxins: Not well studied

• Notes: Rare indoor finding — more indicator of wood moisture than infestation.

Botrytis

• Scientific: Botrytis cinerea

• Common Name: Gray Mold

• Habitat: Fruits, vegetables, flowers

• Indoor Substrates: Food storage, produce drawers

• Water Needs: High

• Spread: Spores through handling/agriculture

• Allergen Risk: Moderate

• Toxins: Rarely relevant

• Notes: Indoor presence = spoiled produce or fresh-cut flower decay.

Brachysporium-like

• Scientific: Brachysporium spp.

• Habitat: Soil, rotting wood

• Indoor Substrates: Very rare

• Allergen Risk: Unknown

• Comments: No significant indoor IAQ relevance.

Cercospora

• Scientific: Cercospora spp.

• Habitat: Agricultural fields, crops

• Indoor Growth: Not on building materials

• Spread: Wind-borne surge during harvest season

• Allergen Risk: Moderate

• Notes: Often spikes seasonally — rarely an indoor problem.

Chaetoconis

• Scientific: Chaetoconis spp.

• Habitat: Plant pathogen

• Indoor Concern: Minimal

• Notes: Not associated with indoor mold issues.

Coelomycete (Group)

• Scientific: Coelomycetes (asexual fruiting-body fungi)

• Habitat: Leaves, stems, plant debris

• Indoor Growth: Slow/rare; not airborne efficiently

• Dissemination: Splash/wind outdoors

• Notes: Not IAQ-significant unless found in extreme numbers.

Curvularia

• Scientific: Curvularia spp.

• Habitat: Tropical/subtropical foliage

• Indoor Substrates: Rare – occasionally wet textiles

• Spread: Airborne outdoors

• Allergen Risk: Moderate–high

• Notes: Indoor detection usually tracking from outside.

Epicoccum

• Scientific: Epicoccum nigrum

• Habitat: Decaying vegetation, soil

• Indoor Substrates: Paper, fabrics (rare)

• Spread: Easily airborne outdoors

• Allergen Risk: High — respiratory sensitivity

• Notes: Indoors = normal infiltration unless heavy.

Exosporium

• Scientific: Exosporium spp.

• Habitat: Plant-associated

• Indoor Growth: Extremely rare

• Notes: Not considered a building mold.

Fusicladium

• Habitat: On leaves, crop plants

• Indoor Relevance: Very low

• Notes: Seen frequently in agricultural regions outdoors.

Lasiosphaeria

• Scientific: Lasiosphaeria spp.

• Habitat: Decaying wood, soil

• Indoor Relevance: Minimal

• Notes: Very low concern for indoor air assessments.

Mitospore (Group)

• Scientific: Asexual spore category (non-identifiable to genus without structures)

• Habitat: Widespread in nature

• Indoor Relevance: Usually background/infiltration

• Allergen Risk: Varies

• Notes: Common in lab reports as unidentified asexual spores — not diagnostic alone.

Myrothecium

• Scientific: Myrothecium spp.

• Habitat: Soil, plant surfaces, crop residue

• Indoor Growth: Rare but can occur on damp textiles or wood

• Allergen Risk: Low–moderate

• Toxins: Some species produce trichothecene toxins

• Notes: More relevant agriculturally than in homes.

Nigrospora

• Scientific: Nigrospora spp.

• Habitat: Tropical and warm climates; soil

• Indoor Growth: Minimal indoor colonization

• Allergen Risk: Moderate

• Notes: Indoor presence typically reflects open windows or outdoor airflow.

Oidium (Powdery Mildew)

• Scientific: Oidium spp.

• Common Name: Powdery Mildew

• Habitat: Plant pathogen on foliage

• Indoor Growth: Does not colonize building materials

• Notes: Indoor presence = plant contamination (houseplants).

Paecilomyces

• Scientific: Paecilomyces spp.

• Habitat: Soil, foods, decaying plants

• Indoor Substrates: Spoiled food or dusty insulation (rare)

• Allergen Risk: Moderate; opportunistic infection in immunocompromised

• Toxins: Some species produce metabolites

• Notes: Spores resemble Aspergillus/Penicillium — may require expert ID.

Peronospora (Downy Mildew)

• Scientific: Peronospora spp.

• Common Name: Downy Mildew

• Habitat: Foliar plant pathogen

• Indoor Growth: None on building materials

• Notes: Appears when garden vegetation is nearby.

Pestalotiopsis

• Scientific: Pestalotiopsis spp.

• Habitat: Plants, decaying leaves

• Indoor Relevance: Very low

• Unique Note: Some strains can digest synthetic polyurethane

• Comments: Rare but interesting environmental mold.

Pithomyces

• Scientific: Pithomyces spp.

• Habitat: Grass, plant litter, soil

• Indoor Growth: Possible on damp paper occasionally

• Allergen Risk: Mild

• Notes: Indoor presence usually normal infiltration.

Polythrincium

• Scientific: Polythrincium spp.

• Habitat: Plant surfaces

• Indoor Relevance: None known

• Comments: Not associated with human IAQ issues.

Pyricularia

• Scientific: Pyricularia spp.

• Habitat: Grains, rice crops

• Indoor Growth: None typically

• Notes: Agricultural mold — indoor presence = door/window exchange.

Smut / Periconia / Myxomycete-like

• Group Description: Plant parasites/pathogens with similar round brown morphology

• Habitat: Fields, grasses, forest floors

• Indoor Relevance: Very low unless extremely elevated

• Notes: High indoors may indicate air infiltration from exterior.

Spegazzinia

• Scientific: Spegazzinia spp.

• Habitat: Rotting wood, vegetation

• Indoor Growth: None

• Notes: Distinct lobed spores — fun to show clients under microscope.

Stemphylium

• Scientific: Stemphylium spp.

• Habitat: Plant material

• Indoor Growth: Rare; occasionally on wet textiles

• Notes: Mimics Alternaria/Ulocladium visually.

Torula

• Scientific: Torula spp.

• Habitat: Plants, decaying foliage

• Indoor Relevance: Minimal unless very high indoors

• Allergen Risk: Moderate

• Notes: More common near agricultural zones.

Trichocladium

• Scientific: Trichocladium spp.

• Habitat: Marine wood, wetlands

• Indoor Relevance: Extremely rare

• Notes: Appears sometimes in drain flies or wood stored outdoors.

Unidentified Spore

• Meaning: Fungal spore observed, lacks ID markers

• Relevance: Not diagnostic alone

• Use: Evaluated using ratios & context, not standalone.

Urediniospores (Rust Spores)

• Scientific: Rust fungi spore stage

• Habitat: Crops, grasses

• Indoor Growth: None

• Herald: Often elevated after windstorms/rain

• Notes: Usually harmless indoors.

Zygomycetes Group

• Included Genera: Mucor, Rhizopus, etc.

• Habitat: Soil, compost, manure

• Indoor Growth: Spoiled foods, high humidity

• Spread: Rapid sporulation

• Notes: Presence indoors often indicates food spoilage, not wall growth.

Zygophiala

• Scientific: Zygophiala jamaicensis (common species)

• Habitat: Plant leaves

• Indoor Relevance: Minimal

• Notes: Known for sooty blotch on fruit surfaces.

Background Particulates