Forenisc BotanySpring 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 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

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

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

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

Pollen ProducersNon-seed Plants Seed Plants

FernsMossesLiverwortsHorsetailsClub mosses

GymnospermsCycadsGinkgoesConifers

AngiospermsFlowering plants

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

Gymnosperms

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

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.

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.

Angiosperm Fruit

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.

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

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

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

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

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.

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

Spore Producers Fungi- include

baker’s yeast, mold and mushrooms

Produce spores sexually and asexually

Released by wind and water

Are found everywhere

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)

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.

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.

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.

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

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