What is Forensic Botany?
Forensic botany is the application of plant sciences to criminal investigations. A relatively new discipline, forensic botany 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), and molecular biology
Use of Botany in Forensic Science:
Botanical evidence:
Botanical evidence can also be used to identify clandestine graves. When soil is disturbed, certain plants quickly invade the fresh surface. Other species follow in succession until the area recovers. However, the composition and distribution of the new assemblage is never exactly the same as the original community. In addition, the presence of a buried body may chemically change the soil and either promote or inhibit growth. Either way, the disturbed area will be at a different stage than its surroundings. These differences may be visible for decades.
Botanical evidence and estimating time elapsed since death
Aquatic species can also be helpful. For example, algae and diatoms can be used to diagnose death by drowning in freshwater. To establish drowning, botanists identify the number and species of diatoms present in the lungs and other tissues and correlate them with the flora from the location the individual was found. Because algae and diatoms vary seasonally, their abundance and diversity in an area can also approximate time since death or generate a 'signature' of an aquatic habitat that can match a body to a given location.Trees and roots are useful for determining elapsed time since death, time since a body was placed at a given location or the season in which a death occurred. Because woody plants and trees grow in annual cycles that vary with environmental conditions, growth rings can be counted to provide the timing of an event, sometimes centuries later. This is particularly accurate if the roots grow through clothing or bone. Even partial damage to root growth can suggest the period since an interruption occurred
Wood
Wood variety as well as wood grain and knots can also act like a fingerprint in the solving of a crime. It was the wood of a ladder that led to the conviction in 1935 of Bruno Richard Hauptmann for the 1932 murder of the Lindbergh baby.
Dendrochronology is the study of tree rings for forensic purposes. A related science is the study of wood rings in connection with soil contamination. An example is the presence of arsenic. Dendrochronology can provide much information with regard to the cultural sciences, as well.
Leaves
Of course the shape of a leaf can lead to its being identified, but the type of tree a leaf comes from isn’t the limit to its usefulness. In some instances, DNA analysis can establish a leaf associated with a criminal suspect comes from a specific tree at the scene of a crime. It is of special interest that, not only fresh, but dried leaves can be used in forensic biology for DNA evaluation.
Seeds
In May 1992, a dead woman was found in an Arizona desert near a Palo Verde tree that had a fresh abrasion on it. Later, a suspect was found who had a seed pod from a Palo Verde tree found in his truck. RAPD (Random Amplified Polymorphic DNA) analysis revealed the seeds in the truck were almost certainly from the identical tree associated with the victim. Conviction was obtained.
