Forensic Botany
Where Plant Science Meets Criminal Investigation
What is Forensic Botany?
Forensic botany is the application of plant sciences to criminal investigations. This relatively new discipline incorporates several subdisciplines:
Palynology
The study of pollens
Dendrochronology
The study of tree rings
Limnology
The study of aquatic environments
Systematics
The classification of plants
Ecology
The study of ecosystems
Molecular Biology
The study of biological molecules and their interactions
Applications in Forensic Science
Botanical evidence can help identify hidden graves through several mechanisms:
- When soil is disturbed, certain plants quickly invade the fresh surface
- Other species follow in succession until the area recovers
- The composition of the new plant assemblage is never exactly the same as the original community
- A buried body may chemically alter the soil, promoting or inhibiting growth
- These disturbed areas may remain visibly different for decades
Estimating Time Since Death
Aquatic species provide valuable forensic information:
- Algae and diatoms can diagnose death by drowning in freshwater
- Forensic botanists identify diatoms in lungs and tissues
- These can be matched with flora from the location where a body was found
- Seasonal variations can approximate time since death
- Aquatic plant profiles can generate a "signature" matching a body to a specific location
Trees and roots offer temporal evidence:
- Growth patterns help determine elapsed time since death
- Annual growth cycles vary with environmental conditions
- Growth rings can be counted to establish timing of events
- Root growth through clothing or bone provides particularly accurate timing
- Even partial damage to roots can suggest when an interruption occurred
Key Botanical Evidence Types
Wood
- Wood variety, grain patterns, and knots can function like a fingerprint
- In 1935, wood evidence from a ladder led to Bruno Richard Hauptmann's conviction for the 1932 Lindbergh baby murder
- Dendrochronology (study of tree rings) has forensic applications
- Related techniques can identify soil contamination (e.g., arsenic presence)
Leaves
- Leaf morphology enables plant identification
- DNA analysis can link a leaf to a specific tree at a crime scene
- Both fresh and dried leaves can yield viable DNA for forensic evaluation
Seeds
Seeds can provide crucial evidence in criminal investigations.
Case Study: Arizona, May 1992
- A woman's body was found near a Palo Verde tree with a fresh abrasion
- Investigators later found Palo Verde seed pods in a suspect's truck
- RAPD (Random Amplified Polymorphic DNA) analysis matched the seeds to the specific tree at the crime scene
- This botanical evidence helped secure a conviction
