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Forenisc Botany

Forenisc Botany. Spring 2013. Forensic Palynology. The use of pollen and spore evidence to help solve criminal cases. Some Vocabulary. Angiosperm- a flowering plant that produces seeds within a fruit Exine - outer layer of the wall of a pollen grain or spore

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Forenisc Botany

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  1. Forenisc Botany Spring 2013

  2. Forensic Palynology • The use of pollen and spore evidence to help solve criminal cases

  3. Some Vocabulary • Angiosperm- a flowering plant that produces seeds within a fruit • Exine- outer layer of the wall of a pollen grain or spore • Gymnosperm- a plant with naked seeds that not enclosed in a protective chamber (fruit), such as an evergreen • Pistil- the female reproductive part of a flower where eggs are produced

  4. Some Vocabulary • Pollen “fingerprint” (aka pollen profile)- the number and type of pollen grains found in a geographic area at a particular time of year • Pollen grain- a reproductive structure that contains the male gametes of a seed plant • Pollination- the transfer of pollen from the male part to the female part of a seed plant

  5. Some Vocabulary • Spore- an asexual reproductive structure that can develop into an adult found in certain protists (algae), plants, and fungi • Stamen- the male reproductive part of the flower consisting of the anther and filament where pollen is produced

  6. Pollen Producers • The plant kingdom is broken down into 2 groups: non-seed plants and seed plants • The earliest plants were non-seed plants, they reproduced using spores • Seed plants make pollen to disperse male gametes (“sperm”) • There are 2 groups of seed plants: angiosperms and gymnosperms • Both types are land plants are likely to leave trace evidence

  7. Pollen Producers

  8. Gymnosperms • Gymnosperms are the oldest seed plants • Seeds are exposed to the outside and not enclosed (like in angiosperms) • Called “evergreens” because they retain their leaves and needles throughout the year

  9. Gymnosperms

  10. Gymnosperms • Many conifers produce seeds with a hard cone. • Female cones- Larger & open. Contain eggs Inside ovules. • Male cones- Smaller & occur in clusters. Release large amounts of pollen to be spread by the wind.

  11. Angiosperms • Flowering plants that produce seeds in enclosed fruits • Include corn, maples, oaks, and grasses. • Very successful and widespread group with over 300,000 species known. • Because angiosperm plants are found in so many places, many different crime scene areas are likely to contain samples of angiosperm pollen.

  12. Angiosperms • Pistil is the female part. • Stamen is the male part. • Pollen lands on the stigma and travels down the style to the ovary. • There may 1 or hundreds of egg-containing ovules within the ovary.

  13. Angiosperm Fruit

  14. Pollination • Pollen dispersal patterns are an important consideration at a crime scene. The pollination strategy of a plant is important in determining the presence or absence of pollen in a place or on an object at the scene.

  15. Pollination • Self-pollination- transfer of pollen from the anther to stigma of the same flower (pea plants) • Cross-pollination- transfer of pollen from the anther of one plant to the stigma of another plant • Some plants perform both pollinations • Self-pollinating plants are of lower value in forensics because they produce less pollen and exist in small numbers

  16. Methods of Pollination • Wind • Generally have small, non-fragrant flowers • Animal (insects, birds, bats, monkeys) • Flowers of these plants must be very fragrant and colorful! • Water • Sea grasses, composed only of a single-layered cellulose wall

  17. Wind Pollination • Wind-pollinated plants produce large amounts of pollen • This allows them to be well represented at a crime scene • This could make it less effective for determining links between individuals and places

  18. Animal Pollination • Make adhesive and durable pollen • This allows them to be more likely collected as evidence • Can provide strong evidence of contact because the pollen can only be directly transferred • Animal-pollination plants produce less pollen so they tend to be under-represented at a crime scene

  19. Water Pollination • Aquatic plant pollen is release under the water which means it is rarely preserved and generally decomposes if removed from the water. • Very limited use for forensics • An exception would be drowning victims. Contents of lungs could be examines for pollen and other debris.

  20. Spore Producers • Include certain protists (algae), plants, fungi and some bacteria • Algae- spores are adapted for dispersion in water or air • Land Plants- produce spores from a structure called sporangium, gills or sori. • Ferns and mosses release spores into the air

  21. Spore Producers • Fungi- include baker’s yeast, mold and mushrooms • Produce spores sexually and asexually • Released by wind and water • Are found everywhere

  22. Spore Producers • Bacteria- Some bacteria form thick-walled, resistant spores, called endospores when environmental conditions are harsh • Endospores are different from other spores because they are not used in reproduction. The bacteria only produce 1 at a time. • These are important to forensics because several types of bacteria have been used as bioterrorism agents (anthrax and botulism)

  23. Pollen & Spore Identification in Solving Crimes • The exine (hard, outer layer) of pollen and spores is unique to plants. • Looking at shape, size, wall thickness and surface texture (such as spines) can help determine type/species of plant. • Example: Large pollen from corn cannot travel far (about ½ mile in the wind). If a body had corn pollen on them, then they were probably close to a corn field or flower.

  24. Pollen & Spore Identification in Solving Crimes • Wind-dispersed pollen and animal-dispersed pollen are both easily preserved for identification. • Spores are smaller than pollen and produced in a much larger number. Spore evidence can be harder to find if it is not concentrated. • Spores are more difficult to identify than pollen as far as species.

  25. Pollen & Spore Identification in Solving Crimes • Both pollen and spores are both good for season and geographical location identification • An indication a body has been moved is evidence of spores or pollen not native to the crime scene • Both pollen and spores are hard for criminals to eliminate because they are microscopic • Most pollen and spores are resilient to dehydration and degradation. • Criminals can easily pick these up on their shoes and clothes.

  26. Where can you find pollen and spores? • Living and decaying plant matter • Soil, dirt, mud, dust • Hair, fur, feathers • Clothing, shoes, blankets, rugs, carpet, rope • Victim’s skin, hair, nails, nasal passage, lings, stomach, intestines and fecal matter • Paper, money, packaging material

  27. Where can you find pollen and spores? • Vehicles • Furniture • Air filters in cars, homes, planes • Cracks and crevices of floors, walls, roofs and fences • Drug resins • Honey and other food

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