Chapter 5 Forensic Botany

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Chapter 5 Forensic Botany
By the end of this chapter you will be able to:
5.6 Explain why botanical evidence is often overlooked.
5.7 Summarize the differences between botanical evidence collection and habitat sampling.
5.8 Describe the correct procedures for collecting, labeling, and documenting botanical evidence.
5.9 Explain why a forensic botanist should consult with local individuals; meteorologists; and entomologists,
anthropologists, and wildlife specialists when processing a crime scene.
Introduction
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Forensic botany is the application of plant science to crime-scene analysis for use in legal cases.
Botanical evidence can help answer the following questions:
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Where?
When?
Who?
What was eaten before death?
Was the body moved?
PMI?
History of Forensic Botany
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Plato’s Phaedo
Socrates’ self-administered death sentence of poison hemlock
Richard “Bruno” Hauptmann was convicted of the kidnapping of Charles Lindbergh's son.
This was the first time that forensic botany evidence was accepted as legal evidence during a trial.
The annual rings in a tree are made of xylem cells.
The larger spring growth rings are usually lighter than the darker xylem cells produced during the summer.
The size of each annual ring is affected by local environmental conditions.
How Forensic Botany is Used to Solve Cases
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Plants grow in assemblages.
o Assemblages are groups of plants usually dominated by one species.
Drowning Victims
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By comparing the number and proportion of algae and diatoms in a drowned person’s lungs and body
tissues, it is possible, in some cases, to determine where he or she drowned.
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Fewer than 20 different species of diatoms indicate a recent drowning; more than 50 species indicate a
longer postmortem interval.
Information from Gastric Contents
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Plant cells, with their cellulose cell walls, can easily withstand digestion.
o Dr. Jane Bock and her students created a lab manual to assist in the identification of plant cells in a
person's last meal.
o The manual was used to estimate postmortem intervals based on the degree of digestion.
Secrets from a Grave
o In an old gravesite, the actual site sinks into and fills the grave as the ground settles.
o A new gravesite can be recognized by:
 A mound of soil
 An absence of vegetation
o Different plants on the gravesite than the established dominant plants in the area
Botanical Crime-Scene Analysis
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The crime-scene photographer should take images of:
Dominant plants and other plants
Depressed grasses indicating possible entrances or exits
Broken branches or disturbed plants
Plants that seem unusual for the area
Plants in unusual locations relative to the body, vehicle, or object
Searching for and Mapping Botanical Evidence
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Botanical evidence should be labeled with the following information:
o Description of the plant
o Height of the plant
o Color and shape of flowers, fruits, seeds, stems, and leaves
Botanical Evidence Collection
o At least 10 different types of plants from the areas assemblage, called a habitat sample, should be
collected.
o Botanical evidence is best placed in paper.
o Plants can be temporarily stored using a plant press.
Pollen and Spores in Forensics
o Forensic palynology is the study of pollen and spore evidence to help solve criminal cases.
o Pollen and spores have different functions, but they have similar characteristics.
Pollen Producers
o Plant reproduction is either from non-seed plants or seed plants.
o Pollen Fingerprint:
Seed plants today include:
o Gymnosperms:
o Angiosperms:
The basic reproductive unit of the angiosperm is the flower.
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Types of Pollination
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o Self-pollination
o Cross-pollination
o Some plants can both self- and cross-pollinate.
Methods of Pollination
o Pollen can be carried by wind, animals, or water.
o Wind-pollinated plants are often dominant in the pollen profile of a crime scene.
o They may actually be overrepresented in collection samples.
o They may be less effective for determining direct links between individuals and places.
o Animals can pollinate flowering plants.
Spore Producers
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Spores are asexually reproductive structures produced by a variety of organisms.
Pollen and Spore Identification in Solving Crimes
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Spores are:
o Much smaller and more difficult to identify than pollen grains
o Produced in far greater numbers than pollen
Pollen and Spore Evidence at Crime Scenes
o Finding Pollen and Spores
o Collecting Pollen and Spores
o Analyzing Pollen and Spores
Summary
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Forensic botany and forensic palynology can provide information about the geographic origin of a crime and the
time or season when it took place.
Knowing a crime-scene’s assemblage of plants can help narrow down its location.
Forensic botany can help solve crimes based on plant evidence found on or in a victim, on the suspect(s), or at
the crime scene(s).
Pollen is a reproductive structure containing male gametes that is produced by seed plants. Spores are
reproductive cells produced by algae, fungi, and nonseed plants such as ferns and mosses.
Seed plants including gymnosperms (cone-bearing plants) and angiosperms (flowering plants) produce pollen.
Plants may disperse pollen in the wind or by the movements of animals.
Pollen from wind-pollinated plants is more common in forensic samples, but pollen from insect-pollinated plants
tends to provide more specific information about location.
Pollen evidence collected at a crime scene must be compared with baseline samples from the area.
Collection of all botanical evidence must be performed carefully to avoid contamination.
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