POLLEN AND SPORE EXAMINATION

INTRODUCTION Pollen and spore information can be used to

determine the following: Was the body moved? Where did the crime take place? What season did the crime take place? Did the crime take place in the day or night?

Forensic Palynology – study of pollen and spore evidence to help solve a crime.

Pollen – contains 2 sperm from seed plants Seed – a fertilized egg. Will develop into an

adult plant. Spore – small structure that grows and

develops into an adult in algae, ferns, moss, and fungi (like a seed).

POLLEN PRODUCERS

Pollen “fingerprint” – number and type of pollen grains found in an area at a particular time of year.

Plant kingdom is divided into two groups based on how they reproduce: seeds or spores.Seeds: Gymnosperms

(evergreens) and Angiosperms (flowering plants)

Spores: Ferns, moss

GYMNOSPERMS Means “naked seed” – the seed is not

protected like they are in flowering plants Most numerous group of gymnosperms are

the conifers (evergreens) Produce their seeds within a cone. Here’s

how: Pollination occurs when pollen lands on a female

cone, grows and releases the sperm near the egg.

Once the egg is fertilized, a seed develops (containing an embryo)

ANGIOSPERMS Flowering plants Produce seeds within an enclosed fruit Parts of a flower:

TYPES OF POLLINATION Important in forensics in determining

the presence or absence of pollen in a place or on an object of a crime scene

Self pollination vs. Cross pollinationSelf – pollen transfer from anther to

stigma within the same flower.Cross – pollen transfer involving two

distinct plantsSelf pollinating plants has lower

value because they produce less pollen

METHODS OF CROSS POLLINATIONWind pollination – produce a lot of pollen (good and

bad)

Good – well represented in the pollen profile of a crime scene

Bad – less effective in determining direct links

Flowers are usually nonfragrant, lack color, small

Animal pollination– insects, birds, bats, monkeys

Flowers are fragrant and “showy” Pollen grains are durable and can adhere to

thingsStrong evidence of contactProduce less pollen

POLLEN GRAINS UP CLOSE

METHODS OF POLLINATION CONTINUEDWater pollination

Rarely preserved because it is composed of only a single layer cell wall made of cellulose

Pollen will decompose if removed from water

Limited use, excepts for drowned victims…contents of the lung can be emptied and analyzed.

SPORE PRODUCERS

Algae Adapted for dispersal in water or air

Ferns and Mosses Release spores into the air Because of this, forensics is most interested in these,

why? Fungi

Produce a large amount Mold, yeast, mushrooms Can be found practically everywhere, not so

interesting, why?

Mushroom spores

SPORE DISPERSAL

Wind Water Spore ejection Animal disperal (they eat the

spore and deposit it somewhere else in their feces)

Spore analysis has one advantage over pollen…it is possible to grow the organism and identify the species exactly.

POLLEN AND SPORE IDENTIFICATION IN SOLVING CRIMES

Exine -- The hard outer layer of a pollen or spore grain Has a unique and complex structure under the

microscope. Larger pollen grains can’t travel far (can only

drift with the wind ½ mile) (corn) Wind-dispersed pollen grains are simple,

have thin walls, easily preserved Animal-dispersed pollen grains are large,

sticky, highly ornamented, thick-walled and easily preserved

POLLEN AND SPORE IDENTIFICATION IN SOLVING CRIMES CONTINUED

Identification of pollen and spore grains is species specific Help determine season Help determine location If not native to the crime scene, body was

moved. Pollen and spores are difficult to eliminate by

the suspect because they are microscopic They are resistant to dehydration and

decomposition (can be found in sediment from millions of years ago)