Botanical Remains: Pollen, Seeds and Other Remains

The study of plants and plant remains to aid in criminal investigations is known as Forensic Botany. This branch of Forensic Science involves examining all parts of plants, such as the leaves, stems, twigs, seeds, fruit, pollen and spores and applying this knowledge to cases as needed. Though plants are found nearly everywhere on the planet, they are often very distinctive in various environments and generally occupy specific habitats. Identifying a plant and where it is generally found, or not found, can help to pinpoint locations in an investigation. For example, finding an unusual type of pollen in the clothing of a deceased person can be very significant. Imagine if that pollen is not typically found within 500 miles of the area where the body was found; one would have to question how the body could have come to rest in that location given that the pollen would be considered virtually foreign to that area. Investigators would use this information to trace and pinpoint possible locations of where this person may have been before death to accumulate the pollen to see if they can generate any leads. Not all situations involving foreign matter, such as pollen, indicate foul play.

For example, if the person was traveling to or from a different geographical area that day by airplane, it might be an explanation as to why the clothing was covered in pollen from a distant location. However, if no other explanation can be found and the deceased isn't identified locally, it certainly raises a red flag and becomes suspicious to investigators that the body may have been moved. Forensic Botanists are consulted on cases like the one above to identify the exact type of pollen, the time of year it is generally present, where it is normally found, and other important data related to the decedent or suspect that can be extrapolated from the available plant evidence. Pollen evidence, though helpful in pinpointing locations and seasons, is also easily contaminated. For example, pollen can travel great distances both outward from the center of where it was released and upward into the atmosphere. For example, wind can blow pollen hundreds of miles from where it was originally released, so other areas of the environment near the body must be examined for matching pollen grains. Pollen evidence should be considered, but not fully relied upon, as the only factor in determining locations. Other corroborating factors should be used to help refine a timeline or location suspected in a case. Seeds and fruit, for example would be other forms of plant evidence that could reinforce or refute existing hypotheses during the investigation. Seeds or seed pods may collect on the decedent's clothing as well as the suspect's clothing if they proceeded through a wooded area; it is very common to find "hitch-hiking" plants such as the ones pictured at right.

Finding the same seed pod on both the decedent and the suspect could be considered a link and should be investigated more thoroughly for other evidence that may provide more information.

Check out some real scenarios in which pollen and plant evidence helped to solve the case!

-An intruder entered a home to steal some items. While there, he came across the homeowner and hit the homeowner in the head which resulted in the homeowner's death. As the intruder panicked and left, he tripped over a tropical plant. The plant's pollen transferred to his pants. Forensic Botany pollen specialists known as Palynologists were called in to examine the pollen on the pants. The pollen matched the pollen in the disturbed tropical plant in the home and the intruder was linked to the crime scene.

-Pollen in honey can be tested to find out the country of origin. American Beekeepers generally participate in a farm subsidy program through the US government in which the government will purchase unsold honey at a reasonable market price. Several companies were busted for selling cheaper honey from other countries and bottling it as unsold American honey. When the pollen grains in the honey were tested, they were found to be from other countries, such as China and Argentina, who sold their honey at a much cheaper price.

-Seed pods found only in a wooded area where the victims of a double murder were buried linked the victims and the suspect. The seed pods from the flower known as "White Avens" (Geum canadense Jacq) appeared on the clothing of the victims and the clothing of the suspect. The suspect originally said that the seed pods were common in his backyard and that he got them from there. When investigated, the particular flower and seed pods were only found in the wooded area where the bodies were found. Once pressed during interrogation, the suspect confessed.

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