Pollen as a Forensic Tool in a Zone of Wetlands from Buenos Aires, Argentina

Forensic Palynology is an important tool to resolve the place and sometimes the season of the year of a fact. The palynomorphs may be in different objects (clothes, shoes, ropes). Pollen morphology is sometimes exclusive for a plant species and some of them grow in specific areas besides plants produce pollen at certain times of the year. The study was based on field work and monitoring seasonal wild communities near Punta Lara reserve. This paper describes the pollen morphology of the representative species which grow in this zone of wetlands from Buenos Aires, Argentina and can be representative of the landscape of the region.


Introduction
Pollen is an important tool to recognize the site of a fact and it may contribute to the moment, too. Pollen morphology is sometimes exclusive for a plant species and some of them grow in specific areas besides plants produce pollen at certain times of the year [1][2][3][4][5][6]. A new A new broader term, Forensic Ecology, includes information about sampling strategies for diatom analysis, pollen and soils samples and entomology [7].
In 1959 a murder placed at the herbarium of the Swedish Museum of Natural History was elucidated by the presence of pollen grains of Trifolium pratense and spores of a phycomycete, Endogene [8,9], cultivations areas of Cannabis sp. were detected by the analysis of the pollen associated with the cultivation areas of this drug [5,9]. Several cases were solved through palynology [10], but still it is necessary to spread its importance due to in many countries the court do not know it.
In Argentina, a country with extensive latitude and longitude, there are different phytogeographic regions that can be differentiated by their flora, these phytocoenoses show the association of these plants growing together and brings important data [11,12].
In the Pampean region the vegetation is very heterogeneous, mainly plains or prairies with few lagoons scattered in it. On the northeastern margin is the Rio de la Plata, an area that changes the landscape for its jungles in gallery. This marginal forest belongs to the phytogeographical district of the mixed forests of the Paraná phytogeographic province, and its species descend through the jungle galleries bordering the Uruguay river, and to a much lesser extent the Paraná river from Misiones province [12][13][14][15]. In this place because of its landscape, to be a protected area with scarce human settlements and more easily to hide, have appeared several bodies without life [16][17][18].
The objective of this work is to provide the floristic data of the most representative species and the pollen morphology of some of them.

Materials and Methods
The study was based on field work and monitoring seasonal wild communities near Punta Lara reserve, during four years. Plants specimens were obtained and send to the LEAVES herbarium. For SEM observations, pollen samples were mounted without treatment on metal stubs with adhesive double sided tape, covered with gold/ palladium under vacuum, and examined by a Jeol T100 microscope of the Electronic Microscopy Service from the Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Argentina.

Results
Eight botanical families were selected in this area because they presented interesting pollen morphology due to the possibility of recognizing the plants from which the pollen samples originated.  inhabits marshes such as swamps and uncrowded rivers. In the province it is found in the zone of the Delta and coast of Río de La Plata. Pollen grains with boat shape, negative ornamentation formed by foveas ( Figure 2D).

Discussion
The pollen grains morphology and characteristics studied in this work confirm their importance as indicators of a wetland environment.
The presence of any of them would be relating the place of the fact to the suspects. The region where these plants grow is well delimited and separates from other nearby with very different vegetation allowing identify the area without doubt. There are many works on pollen of aquatic angiosperms that demonstrate the great diversity that they exhibit in pollen characters, such as types of apertures and sporoderm structure; we can add shape, size and polarity [19]. Several authors have been able to determine that rare or unique species for a geographical area easily confirm the origin of the material; they explain that DNA evidence is sometimes needed [20]. Additionally Sanchez et al. [10] have shown that on very close areas of different vegetation the polynic analysis is valid as a method because there is correlation between the pollen spectra of samples in each locality and the pollen present in shoes and on the surface sediment, which suggests that the sediment housed in the sole of the shoe represents the precise delimitation of an important environment in of the forensic context [21].
Environmental profiling have also provided in war crimes the original areas of the graves and relate the relocated bodies to the original burial sites, sometimes also the execution sites [22].
It is important to make pollen diagrams that show the correlation between the current vegetation and the pollen obtained from the analyzed samples. Forensic palynology has presented many evidences of its value as any other forensic tool, since the 60's has grown a lot and is increasing day by day; this allows it to be increasingly recognized.