Forensic botany and pollen master set

How are plants and fungi used in criminal investigations?

Plants and fungi can be used in forensic investigations in several key ways:

1. As physical evidence (trace evidence):

• Whole plants, fragments, pollen, spores, and algae can link a suspect, object, or victim to a specific location.

2. As indicators of time and place:

• Their distribution, seasonality, and growth patterns can help determine:

  • Time since death (PMI/PBI)

  • Location of crime or body deposition

3. As reconstructive evidence:

• Can provide information about:

  • Movement of a body (e.g. reburial)

  • Environmental conditions

  • Circumstances surrounding death

4. As agents of crime (cause of death):

• Certain plants and fungi contain toxins/poisons (e.g. hemlock, poisonous mushrooms) that can be used deliberately or accidentally.

Types of botanical evidence include:

• Whole plants and fungi

• Plant fragments (leaves, seeds, wood, roots)

• Pollen and spores (palynology)

• Algae

Forensic significance:
They provide valuable circumstantial evidence to link people, places, and events, and to help reconstruct crimes

What areas of plant science are used in forensic investigations?

Several specialist areas of plant science are used to analyse botanical evidence:

1. Plant anatomy

• Study of cells and tissues

• Used for analysing stomach contents, plant fragments, and trace evidence

2. Plant physiology

• Study of plant function and growth

• Helps interpret growth rates and environmental responses

3. Plant ecology

• Study of relationships between plants and their environment

• Used to identify habitat, soil conditions, and clandestine graves

4. Plant taxonomy

• Identification and classification of plants to species level

• Essential for linking evidence to specific locations

5. Plant geography (biogeography)

• Study of plant distribution across regions

• Helps determine where a plant originated

Forensic significance:
These disciplines allow scientists to identify, interpret, and link botanical evidence to a location, time, and events in a criminal investigation.

Why are plants and fungi useful as forensic indicators?

Plants and fungi are valuable in forensic investigations due to several key characteristics:

1. Abundance

• There are >400,000 plant species

• Widely available as potential evidence

2. Diversity

• Occur in many different habitats and environments

• Increases the likelihood of location-specific identification

3. Environmental distribution

• Species are linked to specific soils, climates, and habitats

• Can help pinpoint where an event occurred

4. Species-specific characteristics

• Unique morphological features allow identification to species level

• Enables comparison between crime scene and evidence

5. Dispersal adaptations

• Pollen, spores, seeds, and leaves disperse in predictable patterns

• Often seasonal, helping estimate time of year

Forensic significance:
These properties allow plants and fungi to be used to link individuals or objects to a location, and to estimate the timing and environment of an event.

How do the structure and biology of plants and fungi make them useful as forensic indicators?

Plants and fungi are eukaryotic and mostly multicellular organisms with distinct structural and biological features that make them valuable in forensic investigations.

1. Cellular structure and DNA

• Contain abundant DNA (nuclear, chloroplast, mitochondrial)

• DNA can be used for species identification and comparison

• Cell walls (cellulose in plants, chitin in fungi) help preserve cells and DNA better than animal tissues

2. Growth patterns (roots and tissues)

• Roots grow through soil and around objects

• Can indicate burial timing (post-burial interval) and disturbance of soil

• Growth rates and structures can help estimate time since deposition

3. Seasonal development

• Plants produce leaves, flowers, fruits, and seeds at specific times of year

• Fungi may produce fruiting bodies under certain seasonal and environmental conditions

• These features can help estimate time of year (months/weeks)

4. Environmental specificity

• Species grow in specific habitats and soil types

• Presence of certain plants/fungi can indicate location of a crime or body

Forensic significance:
The structure, growth, and ecology of plants and fungi allow investigators to estimate time, determine location, and link individuals or objects to a specific environment.

How has forensic botany been used historically in criminal investigations?

Early modern forensic botany (1930s):

• One of the first major cases involved the Lindbergh kidnapping (1932, USA)

• A 20-month-old child was kidnapped and murdered

• A wooden ladder used at the crime scene was analysed

• Botanical analysis showed the wood matched material from the suspect’s attic

• Helped link the suspect to the crime scene

Earlier historical use (Trial by ordeal):

• Plants were used as “truth tests” in the Middle Ages

• Example:

  • Cerbera tanghin (poison affecting the heart)

  • Calabar bean (Physostigma venenosum)

• Outcomes (e.g. vomiting or survival) were used to determine guilt or innocence

Key point:

• Early uses were often unscientific or ritualistic, whereas modern forensic botany is evidence-based and analytical

Forensic significance:
Demonstrates the evolution of plant use from ritual practices to scientific tools for linking suspects, objects, and crime scenes.

Why are plants useful as forensic indicators, and what areas of plant science are applied?

Why plants are useful:

• Plants are ubiquitous in the environment

• They are highly sensitive to environmental changes (e.g. altitude, season, climate)

• Their presence and condition can help pinpoint the time and location of an event

Key forensic disciplines:

1. Plant anatomy

• Study of cells and tissues

• Used in analysis of stomach contents and plant fragments

2. Plant taxonomy

• Identification of species

• Essential for trace evidence comparison and linking to specific locations

3. Plant ecology

• Study of plant–environment relationships

• Used to identify habitats, soil conditions, and clandestine graves

Forensic significance:
Plants can provide circumstantial evidence to help reconstruct events by linking people, places, and time.

How do plant life cycles and reproductive structures act as forensic indicators?

Seasonality of plant growth:

• Plant life cycles are seasonal

• Structures such as leaves, flowers, fruits, and seeds appear at specific times of year

• Can help estimate time of year (months or seasons) of an event

• Variation between years (e.g. fruiting patterns) can provide additional temporal clues

Reproductive structures as evidence:

• Seeds and fruits are:

  • Designed for dispersal (wind, animals, humans)

  • Easily transferred to clothing, shoes, and objects

  • Often dehydrated (~5% water content) → highly resistant and persistent

Spores (bryophytes and ferns):

• Produced in large numbers

• Very small and inconspicuous → easily transferred without detection

• Can provide location-specific information, but may be difficult to detect and collect

Forensic significance:
Plant life cycles and reproductive structures help investigators determine when and where an event occurred, and can act as trace evidence linking individuals to environments.

How are fungi used as forensic indicators?

Fungi are valuable forensic indicators due to their ecological specificity, role in decomposition, and temporal patterns.

1. Spatial (location) indicators

• Fungi grow in specific habitats (e.g. woodland, soil, buildings)

• Certain species are location-specific, helping identify where a crime occurred or a body was deposited

2. Temporal (time) indicators

• Fungal growth is often seasonal

• Can help estimate time of year

• As decomposers, fungi break down organic material at predictable stages, aiding post-mortem interval (PMI) estimation

3. Role in decomposition

• Part of the necrobiome (post-mortem community)

• Decompose tissues and alter soil chemistry

• Can indicate burial sites and changes in soil nutrients

4. Trace and reconstructive evidence

• Fungal spores can transfer to clothing, objects, and environments

• Help link individuals to specific locations

5. Cause of death and toxicology

• Some fungi are poisonous (e.g. death cap mushroom)

• Can be used as murder weapons or identified in stomach contents

Forensic significance:
Fungi provide circumstantial evidence to help determine location, time since death, environmental conditions, and possible cause of death.

How does the fungal life cycle contribute to its use as a forensic indicator?

General lifecycle:

• Fungi have a relatively simple life cycle compared to plants

• Involve spore production → germination → mycelial growth → fruiting bodies (in some species)

1. Temporal (time) indicators

• Fungal growth and fruiting are often seasonal

• Different stages of fungal development can help estimate time since death (PMI) or time of year

2. Spatial (location) indicators

• Many fungi are habitat-specific

• Presence of certain species can indicate environmental conditions and location

3. Spore evidence (trace evidence)

• Fungal spores are:

  • Extremely small and numerous

  • Easily transferred to clothing, objects, and environments

  • Difficult to completely remove, making them valuable trace evidence

• Can help link individuals to specific locations

4. Ecological relationships

• Many plants (~80%) form symbiotic relationships (mycorrhizae) with fungi

• This links fungal presence to specific plant communities and environments

Forensic significance:
The fungal life cycle and spore production allow fungi to provide both temporal and spatial information, helping to link people, places, and events in forensic investigations.

What is the role of fungi in the environment, and how is this useful in forensics?

Ecological role:

• Fungi are heterotrophs and major decomposers

• They break down organic material, recycling nutrients back into the ecosystem

Necrobiome:

• Fungi are part of the necrobiome
  (post-mortem community including bacteria, fungi, arthropods, and other organisms)

• Play a key role in the decomposition of bodies

Forensic applications:

1. Time since death (PMI):

• Fungi colonise and decompose tissues in predictable succession patterns

• Different species appear at different stages of decomposition

• Can help estimate PMI (with caution)

2. Location of body:

• Fungal species are often environment-specific

• Can indicate where a body has been located or buried

3. Soil and environmental changes:

• Decomposition alters soil chemistry and nutrients

• Fungal communities respond to these changes

• Can help identify clandestine graves

Important limitation:

• Decomposition rates vary depending on environmental conditions, so fungi provide supporting (circumstantial) evidence, not exact timing.

Forensic significance:
Fungi contribute to understanding when and where decomposition occurred, helping reconstruct events in forensic investigations.

Which parts of plants and fungi can be used as forensic evidence?

A wide range of plant and fungal materials can be used as forensic evidence, including both natural structures and derived products:

1. Whole plants and fungi

• Entire plants or fungal bodies at a scene

• Can indicate location, habitat, or disturbance

2. Plant fragments

• Leaves, stems, roots, bark, wood

• Useful as trace evidence linking individuals or objects to a location

3. Reproductive structures

• Seeds, fruits, pollen, and spores

• Often abundant, transferable, and persistent

• Useful for linking and timing (seasonality)

4. Wood and plant-derived materials

• Timber, paper, plant fibres, and other products

• Can link objects (e.g. weapons, tools, documents) to a source or location

5. Fungal material

• Fruiting bodies, spores, and mycelium

• Can indicate environment, decomposition stage, and location

Forensic significance:
These materials can act as trace or reconstructive evidence, helping to link suspects, victims, and objects to specific environments and events.

What are the legal applications and evidence considerations in forensic botany?

Legal applications:

• Used in a range of cases, including:

  • Homicide and suspicious death

  • Sexual assault

  • Burglary and drug offences

  • Wildlife and agricultural crime

• Typically provides circumstantial evidence, rarely the sole evidence in a case

Evidence collection considerations:

• Plants are ubiquitous → high risk of contamination

• Must maintain a strict chain of custody

• Evidence should be collected as soon as possible to prevent:

  • Decomposition

  • Transfer or loss of material

Sampling strategy:

• Collect from:

  • Crime scene (soil, water, vegetation)

  • Body and clothing

  • Multiple depths and locations

• Always collect control/background samples

Scene documentation:

• Record:

  • Vegetation present

  • Soil type

  • Environmental conditions (e.g. colour, smell, plant condition such as wilting)

• Use photographs and detailed notes

Preservation:

• Package samples carefully to prevent:

  • Degradation

  • Cross-contamination

Forensic significance:
Careful collection and documentation allow botanical evidence to be used to reconstruct events and link individuals, objects, and locations.

How can whole plants (presence) be used as forensic evidence?

Illegal plant trade (wildlife crime):

• Many plants are subject to illegal trafficking, including:

  • Cycads, succulents, orchids

  • Timber (e.g. hardwood, teak)

• Of ~37,000 species protected under CITES, ~30,000 are plants

• Trade is often high-value and linked to organised crime

• Difficult to detect due to limited public awareness of rare species

Illegal cultivation and contraband:

• Presence of certain plants can indicate criminal activity, e.g.:

  • Cannabis farms

  • Use of plants in drug production or transport

Forensic significance:

• Whole plants can indicate:

  • Presence of illegal activity

  • Type of crime (e.g. trafficking, drug production)

  • Links to organised crime networks

Key point:
The presence of specific plant species can act as evidence of criminal activity, particularly in wildlife and drug-related offences.

How can damage to whole plants be used as forensic evidence?

Damage to plants can provide valuable reconstructive evidence at a crime scene.

1. Evidence of disturbance or struggle

• Broken branches, crushed vegetation, or disturbed plants may indicate:

  • Site of a struggle

  • Violent activity

• Can help reconstruct events leading to death or injury

2. Entry and exit routes

• Patterns of plant damage can reveal:

  • Movement through a scene

  • Direction of travel

• Useful for identifying access routes used by suspects

3. Criminal damage and activity

• Deliberate or accidental damage (e.g. vehicles driving through fields) can indicate:

  • Escape routes

  • Intentional destruction (vandalism or agricultural crime)

• Damage to valuable crops or seed stocks may suggest targeted criminal activity

Forensic significance:
Plant damage provides visual and physical evidence of movement, activity, and disturbance, helping reconstruct the sequence of events at a crime scene.

How can plant evidence be used to reconstruct events at a crime scene? (Case example)

Case summary:

• Elderly man found dead at the foot of a steep hillside

• Autopsy showed:

  • Death not caused by trauma from the fall

  • Evidence of heart disease and hypothermia

Botanical evidence:

• Broken vegetation consistent with a downhill fall

• Victim was clutching leaves, and leaves were found on clothing

• These matched the surrounding vegetation at the scene

Scene reconstruction:

• Three zones identified:

  1. Point of loss of balance

  2. Point of fall

  3. Point of impact

Conclusion:

• Man likely suffered a cardiac event, causing him to fall

• Survived initially but later died from hypothermia

• Coroner ruled accidental death

Forensic significance:
Plant evidence can be used to reconstruct movement and events, helping distinguish between accidental death and foul play.

How can plant growth and changes in vegetation be used as forensic evidence?

Changes in plant growth over time:

• Vegetation shows changes in:

  • Colour

  • Density

  • Phenology (seasonal growth patterns)

• These changes can indicate disturbance and time since an event

Clandestine graves:

• Burial disturbs soil and plant roots, causing:

  • Altered growth patterns

  • Changes in species composition (assemblage)

  • Differences in plant orientation and density

• Decomposition releases nutrients (e.g. carbon, nitrogen), creating a cadaver decomposition island (CDI)

• This leads to distinct vegetation changes above the grave

Role of fungi in decomposition:

• Fungal succession contributes to nutrient cycling:

  • Early colonisers (e.g. deuteromycetes)

  • Ascomycetes break down softer tissues

  • Basidiomycetes degrade more resistant material (e.g. lignin, bone-associated material)

• These processes influence soil chemistry and plant growth

Forensic significance:

• Vegetation changes can help:

  • Identify burial sites

  • Estimate time since burial (PBI/PMI)

• Most useful over months to years, less reliable over very long timescales

Key limitation:

• Plant growth is influenced by environmental factors, so evidence is circumstantial and must be interpreted carefully.

How can light reflectance from plants be used to detect clandestine graves?

Plant reflectance and physiology:

• Plants reflect light differently depending on their photosynthetic activity

• This is influenced by nutrient availability, especially nitrogen

Effect of decomposition:

• A buried body releases nutrients (e.g. nitrogen, phosphorus) into the soil

• Creates a cadaver decomposition island (CDI)

• Plants growing above the grave show:

  • Increased growth and biomass

  • Darker green coloration

Light reflectance patterns:

• Changes in plant health alter reflectance in:

  • Red light

  • Near/far-red wavelengths

• These differences can be detected using:

  • Remote sensing

  • Hyperspectral imaging

Forensic application:

• Abnormal vegetation reflectance can help:

  • Locate clandestine graves

  • Identify areas of soil disturbance

Forensic significance:
Plant reflectance provides a non-invasive method for detecting burial sites based on changes in vegetation health and soil nutrients.

How can plant growth above buried remains indicate a clandestine grave? (Case example)

Case concept:

• Experimental studies used plants (e.g. Begonia species) grown above buried pig remains (human analogues)

Observations:

• Areas above buried remains showed:

  • Increased plant growth

  • Greater density and biomass

• Due to decomposition releasing nutrients (e.g. nitrogen, phosphorus) into the soil
  → effectively fertilising the plants

Environmental influence:

• The extent of growth changes depends on:

  • Soil pH

  • Moisture/humidity

  • Oxygen availability

Forensic interpretation:

• Enhanced or abnormal vegetation growth can indicate:

  • Possible burial site

  • Soil disturbance and nutrient enrichment

Limitation:

• Most useful in the short to medium term (months–years)

• Effects become less distinct over long time periods

Forensic significance:
Plant growth patterns can help locate clandestine graves and provide evidence of prior burial activity.

How can forest canopy analysis be used to detect clandestine graves?

Problem:

• Clandestine graves in forests are difficult to locate due to large, dense areas

Method: Remote sensing (drones + hyperspectral imaging)

• Drones equipped with hyperspectral sensors can detect:

  • Light reflectance patterns

  • Fluorescence spectra from vegetation

Underlying mechanism:

• Decomposition releases nutrients (e.g. nitrogen) into the soil

• This alters tree physiology and growth

• Results in foliar anomalies (changes in leaf colour, health, and reflectance)

Forensic application:

• Detect abnormal vegetation signatures from above

• Identify potential burial sites without disturbing soil

• Allows large-scale, non-invasive searches

Forensic significance:
Hyperspectral imaging enables efficient detection of clandestine graves in large forested areas by identifying vegetation changes caused by decomposition.

How can plant growth patterns be used to identify a primary crime scene and estimate time since deposition? (Case example)

Case summary:

• February 2011: partially skeletonised remains of a girl found in a field in northern Italy

• Victim had been missing since November

Botanical observations:

• Vegetation was mapped in the surrounding area

• No plant growth directly beneath the body, while vegetation was present nearby

• Indicates the body had been lying in that location, preventing plant growth

Forensic interpretation:

• Absence of vegetation confirmed the site as the primary crime scene (not a secondary deposition site)

• Knowledge of local crop species and growth cycles allowed estimation of time since deposition

Time estimation:

• Plant growth patterns suggested deposition occurred between November and February

Outcome:

• Helped narrow missing persons search

• Contributed to identification of the victim

Forensic significance:
Plant distribution and growth patterns can be used to determine whether a body was moved, identify the primary crime scene, and estimate time since deposition.

How are bryophytes (mosses, liverworts, hornworts) used as forensic evidence?

What are bryophytes:

• Include mosses, liverworts, and hornworts

• Reproduce via spores

• Small, simple plants often found in moist environments

Key forensic properties:

1. Environmental specificity (location):

• Grow in specific habitats (e.g. damp soil, rocks, woodland)

• Can help indicate where a person or object has been

2. Temporal indicators (time):

• Show seasonal changes (e.g. greener in moist/winter conditions, drier/brown in summer)

• Can provide clues about time of year

3. Persistence and resilience:

• Highly dehydration tolerant

• Can survive harsh conditions and remain as trace evidence

4. Transfer potential:

• Small and often unnoticed, easily transferred to:

  • Clothing

  • Footwear

• Useful for linking individuals to environments

Forensic significance:
Bryophytes act as trace evidence that can help determine location and environmental conditions, supporting reconstruction of events.

How can bryophytes (moss) be used to reconstruct events at a crime scene? (Case example)

Case summary:

• Young woman found dead at the base of a shopping centre in Italy

• Fall from height (≈3 storeys)

• Area not accessible to the public → unclear if suicide or pushed

Botanical evidence:

• Moss samples collected from:

  • Victim’s shoes

  • Access route (carpet → walkway → railings → rooftop area)

Analysis:

• Moss on shoes matched moss found along a specific path

• Moss also found on the railings

Reconstruction:

• Evidence showed the victim had:

  • Walked the route herself

  • Reached the railings directly

• If pushed, expected different distribution/pattern of transfer

Conclusion:

• Pathway reconstruction indicated self-directed movement

• Death ruled as suicide, not homicide

Forensic significance:
Small plant materials like moss can act as trace evidence to reconstruct movement and sequence of events, helping distinguish between suicide and foul play

How can plant roots be used as forensic evidence?

Key biological features:

• ~80% of plants form symbiotic relationships (mycorrhizae) with fungi

• Roots enable bidirectional movement of water and nutrients

• Root systems include:

  • Fine root hairs (rapid growth, sensitive to environment)

  • Larger structural roots (can show growth patterns over time)

Forensic applications:

1. Estimating time since burial (PBI):

• Roots can grow through and around buried remains

• Extent of root growth can indicate time since deposition

2. Reconstruction of burial events:

• Root patterns can show:

  • Soil disturbance

  • Whether a body was moved or buried in situ

3. Environmental and location information:

• Root structure and condition reflect:

  • Soil type

  • Moisture and climate conditions

• Can help determine where a body has been located

4. DNA analysis:

• Root material contains plant DNA

• Can be used to identify species and link evidence to a specific environment

Forensic significance:
Plant roots provide evidence for time since burial, location, and disturbance, helping reconstruct events at a crime scene.

Key limitation:

• Root growth is influenced by environmental conditions, so estimates are approximate and contextual.

How can plant roots and moss growth be used to estimate PMI? (Case example)

Case summary:

• Fully clothed skeletal remains discovered

• Evidence of:

  • Roots growing through remains

  • Moss growing on bones

Botanical evidence:

1. Root growth:

• Roots had penetrated and grown around the remains

• Indicates the body had been present for a significant period (post-burial interval)

2. Moss growth:

• Moss colonised the bones

• Moss shows predictable growth patterns, including:

  • Initial vertical growth (e.g. “tree-like” structure)

  • Later lateral expansion

• Growth stage can help estimate minimum time since exposure

Forensic interpretation:

• Combining:

  • Root penetration (longer-term indicator)

  • Moss growth stage (surface colonisation timing)

• Allowed estimation of PMI within a defined timeframe

Outcome:

• Time since death estimated using botanical evidence

• DNA analysis used to confirm identity of the victim

Forensic significance:
Plant succession and growth patterns provide minimum time estimates and help reconstruct duration of exposure and burial.

Key limitation:

• Growth rates depend on environmental conditions, so estimates are approximate.

How are fungal spores used as forensic indicators?

Key properties:

1. Ecological specificity (location):

• Many fungal species occupy restricted ecological niches

• Distribution can be geographically limited

• Presence of specific spores can indicate particular environments or locations

2. Temporal information (time):

• Fungal spores are released during specific periods

• Can provide clues about time of year or season

3. Persistence:

• Spores are highly resistant and can remain in the environment for extended periods

• Useful as long-lasting trace evidence

4. Environmental reconstruction:

• Spores can indicate:

  • Current vegetation

  • Previous plant communities

• Helps reconstruct past and present environments

Forensic significance:
Fungal spores act as trace evidence that can help determine location, environment, and timing, supporting reconstruction of events in forensic investigations.

Key limitation:

• Spores can be widely dispersed, so interpretation must consider potential background contamination.

How were fungal spores used as forensic evidence in a wildlife crime case?

Case summary:

• Illegal disturbance of a badger sett (protected under law)

• Suspect found with a shovel containing soil

Forensic analysis:

• Soil from:

  • Badger sett

  • Suspect’s shovel

• Both contained spores of Choiromyces melandriformis (white-veined truffle fungus)

Key features of the fungus:

• Produces distinctive ascospores with peg-like ornamentation

• Rare in the UK

• Forms mutualistic relationships with tree roots (e.g. oak, beech)

Interpretation:

• Badgers forage for truffles and bring them back to their sett

• Presence of the same rare fungal spores in both samples strongly linked:

  • Shovel → badger sett

Outcome:

• Provided strong trace evidence

• Led to first RSPCA conviction for badger sett disturbance

Forensic significance:
Rare and distinctive fungal spores can provide powerful associative evidence, linking suspects, tools, and specific locations.

How can tree bark fragments be used as forensic evidence? (Case example)

Key properties of bark:

• Contains lignin → highly resistant and persistent

• Forms a tough outer layer

• Bark structure is often species-specific

Case summary:

• 20-year-old man found dead in woodland (shot in head and chest)

• Eyewitness claimed victim had been handcuffed to a tree

• Reliability of witness was uncertain

Forensic evidence:

• Bark splinters found on the victim’s body

• Matched the same tree species at the scene

Interpretation:

• Physical transfer of bark confirmed contact with the tree

• Supported the eyewitness account

Conclusion:

• Botanical evidence helped verify events prior to death

• Strengthened the reconstruction of the crime

Forensic significance:
Bark fragments can act as trace evidence, linking victims or suspects to a specific location or object.

Key limitation:

• Must consider background transfer and ensure proper comparison.

How are seeds and fruits used as forensic evidence?

1. Abundance and distribution:

• Widely present in the environment (ubiquitous)

• Dispersed by wind, animals, water, and humans

• Can be found near or far from the parent plant

2. Seasonal variation (time):

• Produced at specific times of year

• Can help estimate season or time of an event

3. Size and visibility:

• Larger than pollen and spores

• More likely to be noticed and potentially removed

• However, still transferable via clothing, footwear, or objects

4. Persistence and durability:

• Often resistant to decay

• Can remain in the environment for long periods

5. DNA analysis:

• Contain plant DNA

• Can be used for species identification and linking evidence to a specific location

Forensic significance:
Seeds and fruits act as trace evidence that can help determine location, movement, and timing, and link individuals or objects to specific environments.

Key limitation:

• Not present year-round, so availability depends on season.

How are seeds transferred and used as forensic evidence?

Transfer mechanisms:

• Seeds can be transferred via:

  • Clothing and footwear

  • Hair and personal items

  • Vehicles and tools

• Movement can occur through:

  • Direct contact (walking through vegetation)

  • Secondary transfer (via another surface or person)

Dispersal and retention:

• Many seeds have adaptations (e.g. hooks, barbs, sticky surfaces)
  → enhance attachment to surfaces

• Can remain attached for extended periods, increasing evidential value

Forensic applications:

• Link a suspect or object to a specific location

• Reconstruct movement pathways

• Support or refute alibis

Strength of evidence:

• Seeds are often more location-specific than pollen

• Their presence can provide strong associative (circumstantial) evidence

Limitations:

• Seeds may be:

  • Deliberately removed due to visibility

  • Subject to secondary transfer

• Interpretation must consider background presence

Forensic significance:
Seed transfer provides valuable trace evidence to link individuals, objects, and environments, aiding reconstruction of events.

How were seeds used as forensic evidence in a criminal case? (Case example)

Case summary:

• 1995, Texas: toddler abducted and sexually assaulted

• Investigation included:

  • DNA evidence

  • Fingerprint evidence

  • Plant material

Botanical evidence:

• Seeds from a specific plant species found:

  • On the suspect’s shoes

  • In the child’s bedroom

Analysis:

• A taxonomist identified the plant species

• Matching seeds provided a link between suspect and crime scene

Forensic interpretation:

• Demonstrated transfer of plant material from scene to suspect

• Supported other evidence (DNA, fingerprints)

Outcome:

• Strengthened the case by providing associative evidence

Forensic significance:
Seeds can act as trace evidence linking individuals to specific locations, especially when combined with other forensic methods.

Key limitation:

• Requires specialist identification (taxonomy expertise)

• Availability of experts may be limited

How can seeds and plant material in the digestive system be used as forensic evidence?

Digestive processes:

• Food is processed through:

  • Stomach → enzymatic digestion and mechanical churning

  • Small intestine → further digestion and absorption

• Gastric transit time varies depending on:

  • Diet, health, lifestyle

  • Meal size and eating patterns

Plant material and digestion:

• Humans cannot digest cellulose

• Plant fragments (e.g. seeds, fibres) often pass through the digestive system relatively intact

Forensic applications:

1. Last meal analysis:

• Identification of plant material can indicate:

  • What was eaten

  • Approximate time of last meal

2. Location and environment:

• Certain plants are region-specific

• Can provide clues about where the individual was prior to death

3. Reconstruction of events:

• Helps establish a timeline before death

• Can support or challenge witness statements or alibis

Forensic significance:
Seeds and plant fragments in the digestive system can provide valuable evidence about an individual’s final movements, diet, and timing of events prior to death.

Key limitation:

• Gastric emptying is highly variable, so timing estimates are approximate.

How can stomach contents analysis be used to estimate time since last meal?

General timeline:

• 0–2 hours:

  • Undigested food present in the stomach
    → Death occurred shortly after eating

• 4–6 hours:

  • Stomach empty, food present in small intestine
    → Indicates further digestion has occurred

• ≥12 hours:

  • Small intestine empty, waste in large intestine
    → Suggests a longer time since last meal

Physiological factors:

• After death, the pyloric sphincter closes, slowing further movement of food

• Degree of digestion and position of food provides a rough estimate

Forensic applications:

• Estimate time of last meal

• Help place an individual at a specific location (e.g. restaurant)

• Narrow down timeline before death

Key limitation:

• High individual variability due to:

  • Diet and meal composition

  • Health and metabolism

  • Lifestyle (e.g. grazing vs large meals)

Forensic significance:
Stomach content analysis provides a useful but approximate timeline, helping guide investigations and support other evidence.

How can stomach contents and plant material be used to challenge an alibi? (Case example)

• Man found dead at home the day after eating hash browns, eggs, and toast

• Had ongoing financial dispute with his wife (motive established)

• Cause of death: blunt force trauma, gunshot wounds, and stun gun injuries

Forensic evidence:

• Analysis of stomach contents confirmed last meal = breakfast

• Food contained traces of onion, despite:

  • Hash browns eaten by the victim not containing onions

• Indicates food was cooked on a shared griddle with onions

Interpretation:

• Linked the victim’s last meal to a specific location/source of food

• Contradicted the alibi of the wife and her new husband

Outcome:

• Botanical/dietary evidence supported timeline

• Helped secure conviction

Forensic significance:
Plant material in stomach contents can provide evidence of last meal, location, and timing, and can be used to support or refute alibis when combined with other forensic evidence.

Key limitation:

• Timing is approximate due to variability in digestion

How are plants and fungi identified and analysed in forensic investigations?

Specialist expertise:

• Identification requires trained forensic botanists/mycologists

• Expertise needed due to:

  • High species diversity

  • Degraded or fragmentary samples

Analytical methods:

• Morphological analysis (anatomy and structure)

• Microscopy (including light and electron microscopy)

• DNA analysis for species identification

Resources and tools:

• Identification keys and reference collections

• Databases for comparison of species and distributions

• Access to specialist institutions (e.g. Royal Botanic Gardens, Kew)

Challenges:

• Samples may be:

  • Damaged or decomposed

  • Difficult to distinguish between similar species

Forensic significance:
Accurate identification of plant and fungal material is essential for linking evidence to specific locations, environments, or events.

Key limitation:

• Requires specialist knowledge and resources, which may not always be readily available

How can fungal analysis be used to determine cause of death? (Case example)

Case summary:

• Toddler died from a severe respiratory condition

• Home environment suspected as a contributing factor

Forensic investigation:

• Samples of black mould collected from:

  • Bathrooms

  • Living areas of the house

• Fungal material also recovered from the child’s lungs

Analysis:

• Mould from the lungs matched mould present in the house

• Indicated prolonged exposure to the same fungal species

Interpretation:

• Chronic inhalation of mould spores led to respiratory illness

• Established a clear environmental cause of death

Outcome:

• Coroner ruled death as respiratory arrest due to long-term exposure to black mould

Forensic significance:
Fungal identification can link environmental exposure to physiological effects, helping determine cause of death.

Key limitation:

• Requires careful differentiation between:

  • Contamination

  • True infection or exposure

How is stable isotope analysis used in forensic investigations?

Principle:

• Compares ratios of stable isotopes (e.g. C, H, O, N) in a sample

• These isotopes are absorbed and incorporated into tissues and materials

Key feature:

• Isotope ratios vary spatially and temporally due to:

  • Climate

  • Geography

  • Diet and environment

Forensic applications:

• Determine geographical origin of:

  • Humans (diet, migration)

  • Plants and food products

• Used in analysis of:

  • Explosives

  • Drugs

  • Wildlife trafficking

  • Food authenticity

Forensic significance:
Stable isotope analysis provides a chemical “signature” that can link samples to a specific environment or origin.

Key limitation:

• Interpretation requires reference databases and may provide regional rather than exact locations

How is forensic botany used to investigate illegal logging and timber trade?

Context:

• Illegal logging is a multi-billion-dollar global industry

• Often linked to organised crime

• Some tree species (e.g. protected hardwoods like mahogany) are illegally harvested

Types of evidence:

• Wood and timber products (e.g. furniture, logs, paper)

• Can be analysed even after processing

Analytical methods:

• Wood anatomy → identify species

• DNA analysis → confirm species and origin

• Stable isotope analysis → determine geographical source

Forensic applications:

• Determine whether timber:

  • Comes from a protected species

  • Was sourced from a specific region or forest

• Verify claims of legal vs illegal origin

Forensic significance:
Botanical analysis can link wood products to illegal logging activities, helping enforce environmental laws and wildlife protection.

Key limitation:

• Requires reference databases and expertise for accurate identification

How are plant and fungal toxins (phytochemistry) relevant in forensic investigations?

Key concept:

• Plants and fungi produce secondary metabolites
  → chemicals used for defence against herbivores and pathogens

Types of compounds:

• Include toxins, poisons, and psychoactive substances

• Can affect the human body due to interaction with biological receptors

Forensic relevance:

1. Cause of death:

• Some compounds are highly toxic

• Can be used in:

  • Homicide

  • Suicide

  • Accidental poisoning

2. Drug use and toxicology:

• Many plant-derived compounds are used as:

  • Illicit drugs

  • Medicinal substances

3. Detection and analysis:

• Identified through toxicological and chemical analysis

• Can help determine:

  • Substance involved

  • Source of exposure

Forensic significance:
Phytochemical compounds can provide evidence for cause of death, poisoning, or drug use, and help reconstruct events leading to death.

Key limitation:

• Requires careful interpretation due to:

  • Natural presence of some compounds

  • Potential post-mortem changes

What is phytochemical analysis and how is it used in forensics?

Definition:

• Phytochemical analysis involves the identification and quantification of chemical compounds (e.g. toxins, drugs) produced by plants and fungi

Analytical techniques:

• Chromatography (e.g. GC, HPLC) → separates compounds

• Mass spectrometry (MS) → identifies molecular structure

• Spectroscopy (e.g. UV, IR, NMR) → characterises chemical properties

• Immunoassays → detect specific substances

Forensic applications:

• Detect and identify:

  • Poisons and toxins

  • Plant-derived drugs

• Determine:

  • Cause of death (toxicology)

  • Exposure to substances

  • Source of compounds

Forensic significance:
Phytochemical analysis provides chemical evidence to support investigations involving poisoning, drug use, and environmental exposure.

Key limitation:

• Requires specialist equipment and expertise

• Interpretation may be affected by post-mortem changes and metabolism

How are medicinal plants and narcotics relevant in forensic investigations?

Key principle:

• Many plant-derived compounds are dose-dependent
  → Low doses may be therapeutic
  → High doses can be toxic or fatal

Examples:

• Medicinal plants used for treatment (e.g. analgesics, sedatives)

• The same compounds can act as poisons if misused

Forensic relevance:

1. Cause of death:

• Overdose or deliberate poisoning can lead to:

  • Toxic effects

  • Fatal outcomes

2. Drug misuse:

• Plant-derived substances may be used as:

  • Narcotics

  • Recreational drugs

3. Toxicological analysis:

• Detection of compounds helps determine:

  • Dose and exposure

  • Whether death was accidental, suicidal, or homicidal

Forensic significance:
Understanding dose-dependent effects of plant compounds is essential for interpreting toxicity, poisoning, and drug-related deaths.

Key concept:

“The dose makes the poison” (Paracelsus)

How can plant misidentification lead to fatal poisoning? (Case example)

Case summary:

• 41-year-old man died after drinking homemade liquor

• Initial analysis did not reveal cause of death

Forensic investigation:

• Specialist toxicological analysis of blood conducted

• Detected high levels of Gelsemium elegans (highly toxic plant)

Context:

• Lonicera japonica (honeysuckle), an edible plant, was also present in the environment

• The two plants have similar appearance

Interpretation:

• Victim likely mistook toxic plant for edible species

• Consumed it during preparation of homemade liquor

Outcome:

• Death attributed to plant poisoning due to misidentification

Forensic significance:
Accurate identification of plant species is crucial, as visually similar plants can have vastly different toxic properties, leading to accidental poisoning.

Key concept:

• Importance of phytochemical analysis in determining cause of death

How was forensic botany/mycology used in the Erin Patterson mushroom poisoning case?

Case summary:

• Erin Patterson charged with multiple counts of murder and attempted murder

• Victims became ill after consuming a meal containing mushrooms

Claim:

• Patterson stated the mushrooms were dried and purchased months earlier from a grocery store

Forensic investigation:

• A food dehydrator was recovered from a local tip

• Analysis revealed:

  • Mushroom material and spores present on the device

Interpretation:

• Presence of spores suggested recent handling and processing of mushrooms

• Contradicted the claim that mushrooms were store-bought and long-stored

Forensic significance:
Mycological evidence (spores and residues) can:

• Link suspects to handling or preparation of toxic fungi

• Challenge or support statements and alibis

• Contribute to establishing intent and source of poisoning

Key point:
Fungal spores are persistent trace evidence that can remain on objects and provide crucial investigative leads.

DNA analysis for plant and fungal identification

• Plants:
  → Chloroplast DNA (cpDNA) commonly used

  • Highly useful for species identification

  • Conserved but with enough variation for comparison

• Fungi:
  → Ribosomal DNA (rDNA) (especially ITS regions)

  • Widely used for fungal identification

  • Highly variable between species

Forensic significance:
DNA analysis allows accurate identification of plant and fungal species, even from small or degraded samples, helping link evidence to specific environments or sources.

What is metabarcoding and how is it used in forensic plant and fungal analysis?

Definition:

• Metabarcoding analyses DNA from entire communities (mixed/environmental samples)

• In contrast, barcoding identifies a single species

Key features:

• Used for complex samples (e.g. soil, water, gut contents)

• Allows identification of multiple species simultaneously

• Requires reference DNA databases for comparison

Genetic markers:

• Animals: mitochondrial CO1 gene commonly used

• Plants: mitochondrial DNA evolves slowly → use:

  • Chloroplast genes (e.g. rbcL) → high recoverability

  • matK gene → higher resolution

• Standard plant barcode (since ~2009): rbcL + matK combination

Forensic applications:

• Analyse mixed environmental samples

• Identify plant/fungal communities

• Link evidence to specific locations or environments

Forensic significance:
Metabarcoding enables rapid identification of multiple species from trace or degraded samples, improving reconstruction of environmental context and associations.

Key limitation:

• Accuracy depends on quality and completeness of reference databases

What is the metabarcoding pipeline in forensic analysis?

1. Sample collection

• Environmental or mixed sample collected (e.g. soil, water, tissue)

2. DNA extraction

• Total DNA isolated from all organisms in the sample

3. PCR amplification

• Target barcode regions amplified (e.g. rbcL, matK for plants)

4. Library preparation

• DNA fragments prepared for sequencing (adapters added)

5. DNA sequencing

• High-throughput sequencing generates large numbers of DNA reads

6. Data processing and analysis

• Sequences filtered, cleaned, and grouped

7. Comparison with reference databases

• DNA sequences matched to known barcode libraries (e.g. GenBank)

8. Species identification

• Assign taxa based on sequence similarity

9. (Optional) Phylogenetic analysis

• Construct phylogenetic trees to confirm relationships

Forensic significance:
This pipeline allows identification of multiple species from complex samples, helping link evidence to specific environments or locations.

Key limitation:

• Accuracy depends on quality of reference databases and contamination control

How is DNA/metabarcoding used in plant poisoning investigations?

Context:

• Many plant species contain toxic compounds

• Poisoning may be:

  • Accidental (misidentification)

  • Intentional (homicide or suicide)

• Some cases require specific antidotes

Challenge:

• Plant material in:

  • Vomitus

  • Faeces

  • Stomach contents

• Often degraded and unrecognisable, making visual identification difficult

Solution: DNA-based methods

• Barcoding/metabarcoding can:

  • Identify plant (or fungal/animal) species from trace DNA

  • Work on mixed and degraded samples

Applications:

• Determine source of poisoning

• Support toxicological findings

• Help guide medical treatment (antidotes)

Forensic significance:
DNA analysis allows accurate identification of toxic species when morphological methods fail, improving investigation of poisoning cases.

Key limitation:

• Not yet routine practice

• Requires reference databases and specialist analysis

Future potential:

• Increasing use as methods become faster, cheaper, and more reliable

How can metabarcoding of fungal communities be used to estimate PMI? (Case example)

Case concept:

• Study used pig carcasses (human analogues)

• Soil and samples collected at different post-mortem intervals (PMI)

Method:

• Metabarcoding targeting fungal DNA (e.g. ITS regions)

• Identified fungal communities present at different times and locations around the carcass

Findings:

1. Temporal changes:

• Fungal communities changed in a predictable succession over time

• Different species dominate at different stages of decomposition

2. Spatial variation:

• Distinct fungal populations found:

  • On the carcass

  • In surrounding soil

• Created a spatial map of the necrobiome

Forensic interpretation:

• Specific fungi may act as indicator species for certain PMI stages

• Patterns could be used to estimate time since death

Forensic significance:
Metabarcoding allows analysis of entire microbial/fungal communities, providing a potential tool for PMI estimation based on necrobiome succession.

Key limitation:

• Requires:

  • Extensive reference datasets

  • Consideration of environmental variability

• Currently experimental, not routine

Future potential:

• With more data, fungal succession patterns could become a reliable PMI tool

What is forensic botany?

The use of plants and plant material as evidence in criminal investigations.

What is forensic palynology?

The study of pollen and spores in forensic science.

Why is pollen useful in forensic science?

It is microscopic, resistant to decay and species-specific.

What information can pollen provide in investigations?

Location, environment and season of a crime.

Where can pollen evidence be found?

Clothing, hair, shoes and vehicles.

What does finding a single pollen type in cannabis suggest?

An indoor environment.

What does finding multiple pollen types within cannabis suggest?

An outdoor environment.

How can stomach contents help forensic investigations?

Plant material can reveal the victim’s last meal and location before death.

Roughly how many known plant species are there on Earth?

320,000

How can plant ecology – the relationship between plants and their environment – help us in forensic investigations?

Locating clandestine graves

How can plant roots assist in understanding time since burial (PBI)?

Annual growth rings indicate damage

Why are fruits, seeds, and leaves useful in forensics?

Tenacious, Resistant, Size

If the stomach is empty but food is found in the small intestine, roughly how many hours after the last meal did death occur? 

4 - 6h

Which plant naturally contains the poison ricin?

Castor Bean

How should plant evidence be approached at the crime scene?

Environmental controls should be collected, Photography, Documentation in crime scene report, Vegetation surveys completed

Various molecular markers have been tested for plant DNA identification. Which two markers did Ferri et al (2015) identify as most optimal? 

rbcL, trnH-psbA

Which techniques would you use to identify the origin of illegal timber?

Stable isotope analysis, DNA analysis

What is forensic palynology?

The application of pollen and spores in solving criminal and legal issues.

What size range do pollen and spores typically fall within?

5-500 micrometres.

What do pollen grains produce?

Gametophytes that produce male gametes.

Where are pollen grains produced in angiosperms?

In the stamen.

Where are pollen grains produced in gymnosperms?

In cones.

What types of plants produce spores?

Vascular plants (ferns) and bryophytes (mosses).

How many plant species produce pollen?

Over 320,000 species.

What are the three main types of pollination?

Wind-pollinated (anemophilous), animal-pollinated (zoogamous), and self-pollinated (autogamous).

What is the outer layer of a pollen grain called?

Exine.

What features of pollen are useful for identification?

Size, shape, aperture number and type, general pattern/texture, symmetry, and polarity.

What are the limitations of pollen analysis in forensic investigations?

Potential contamination, low taxonomic resolution, and often not being an investigative priority.

What are the advantages of using pollen in forensic investigations?

Its small size, diversity, abundance, resistance to decay, and established techniques.

What challenges are associated with pollen analysis?

Time-consuming analysis and the need for expert knowledge.

What is pollen tenacity?

The ability of pollen to transfer and persist in the environment.

How can pollen analysis assist in product authenticity investigations?

It can determine if products are genuine or falsified, such as in counterfeit medicines, honey. - from the origin they claim to be from.