Chapter 5 Pllen and Spre Examinatin By the end f this chapter yu will be able t: Distinguish between pllen and spres Define a pllen fingerprint Classify the different rganisms that prduce pllen and spres Cmpare and cntrast the female and male reprductive parts in plants Distinguish between gymnsperms and angisperms 1 All Rights Reserved Suth-Western / Cengage Learning 2012, 2009 Frensic Science: Fundamentals & Investigatins, Chapter 5
Chapter 5 Pllen and Spre Examinatin By the end f this chapter yu will be able t: Summarize the different methds f pllinatin and their relevance in slving crimes Identify the different ways spres are dispersed State characteristics f pllen and spres that are imprtant fr frensic studies Summarize hw pllen and spre evidence is cllected at a crime scene Describe hw pllen and spre samples are analyzed and evaluated 2 Frensic Science: Fundamentals & Investigatins, Chapter 5
Intrductin Frensic palynlgy a specialized field that studies pllen and spre evidence Pllen and spres are micrscpic reprductive structure that have resistant structures Pllen cntains the male gametes f seed plants Spres fund in certain prtists, algae, plants and fungi 3 Frensic Science: Fundamentals & Investigatins, Chapter 5
Intrductin Pllen and spre analysis entails Lcard s Principle f Exchange Pllen and spres can help determine: whether a bdy was mved a crime s lcatin in a city r in the cuntry the seasn 4 Frensic Science: Fundamentals & Investigatins, Chapter 5
Pllen-Prducing Plants Pllen fingerprint the number and type f pllen grains fund in a gegraphic area at a particular time f year Nn-seed plants ferns, msses, liverwrts, and hrsetails Seed plants gymnsperms (cycads, ginkges, and cnifers) angisperms (flwering plants) 5 Frensic Science: Fundamentals & Investigatins, Chapter 5
Gymnsperms Gymnsperms are the ldest seed plants Cnifers are the largest grup Seeds are cntained in hard, scaly structures called cnes The male cnes pllinate the female cnes Which cne is female and which is male? 6 Frensic Science: Fundamentals & Investigatins, Chapter 5
Angisperms Flwering Plants The mst recent plant grup t evlve Prduce seeds in an enclsed fruit Very diverse grup (includes crn, aks, maples, and the grasses) Pistil female part Stamen male part Identify the parts in this illustratin 7 Frensic Science: Fundamentals & Investigatins, Chapter 5
Angisperms Flwering Plants 8 Frensic Science: Fundamentals & Investigatins, Chapter 5
Types f Pllinatin Pllinatin the transfer f pllen frm the male part f a plant t the female part f a seed plant Self-pllinatin pllen transfers frm an anther t the stigma within the same flwer, as in pea plants Crss-pllinatin pllen transfers between tw distinct plants 9 Frensic Science: Fundamentals & Investigatins, Chapter 5
Types f Pllinatin 10 Frensic Science: Fundamentals & Investigatins, Chapter 5
Types f Pllinatin 11 Pllen f self-pllinating plants Rarely encuntered Lwer value in frensic studies Pllen can be carried by Wind Animals Water Wind-brn pllen is less effective Ptentially lng distances Frensic Science: Fundamentals & Investigatins, Chapter 5
Spre Prducers 12 Spre prducers include Certain prtists (algae) Plants Fungi Bacteria Bacterial spres, endspres include diseases such as anthrax and btulism Spre advantages Spres can be grwn t increase sample size Identifiable with certainty Frensic Science: Fundamentals & Investigatins, Chapter 5
Spre Dispersal Algae disperse spres int water r air Ptentially large dispersal range reduces value in investigatins Explain hw mushrm spres are released int the wind 13 Frensic Science: Fundamentals & Investigatins, Chapter 5
Pllen and Spre Identificatin in Slving Crimes Angisperm pllen grains Exine Gymnsperm pllen grains Outer shell f a pllen grain and spre Micrscpes reveal cmplex and unique structures Identificatin prvides ptential trace 14 Frensic Science: Fundamentals & Investigatins, Chapter 5
Finding Pllen and Spres 15 Frensic Science: Fundamentals & Investigatins, Chapter 5
Cllecting Pllen and Spres Cntrl and evidence samples must be cllected When cllecting samples: Wear glves Use clean tls Place in sterile cntainers, sealed and labeled Secure and establish a chain f custdy Sampling instruments must be clean r new 16 Frensic Science: Fundamentals & Investigatins, Chapter 5
Evidence Cllectin
Analyzing Pllen and Spre Samples 18 Pllen and spres are chemically extracted frm samples Tls specialists use t examine and identify include: cmpund light micrscpe scanning electrnic micrscpe (SEM) reference cllectins (phts, illustratins, dried specimens) Pllen and spre evidence cllected, analyzed, and interpreted can be presented in curt Frensic Science: Fundamentals & Investigatins, Chapter 5
Analysis - Tls Cmpund light micrscpe Needs X1000 r greater magnificatin Can identify plant family r genus Scanning Electrn Micrscpe (SEM) Up t X100,000 magnificatin Can identify species f plant
Plant Evidence Chlrphyll can smetimes be extracted frm leaves. Different plants cntain different types f chlrphyll, s it can be frensically valuable. Chrmatgraphy techniques can reveal the chlrphyll bands.
.............. Summary.... Frensic palynlgy can indicate smething abut the gegraphic rigin and the time r seasn f a crime. Spres and pllen can be dispersed by wind, by water, r by animals. Pllen frm insect-pllinated plants tends t give mre specific lcatin data than frm wind-pllinated plants. 21 Frensic Science: Fundamentals & Investigatins, Chapter 5
.................. Summary Pllen cllected at a crime scene must include baseline samples frm the area fr cmparisn. Cllectin f pllen and spre evidence must be perfrmed carefully t avid cntaminatin. 22 Frensic Science: Fundamentals & Investigatins, Chapter 5