Phytolith analysis of species of aquatic habitats from SE Buenos Aires province, Argentina.

FERNÁNDEZ HONAINE M., ; ZUCOL A. ; M. OSTERRIETH.

Mar del Plata

Encuentro; 7th IMPR – 4th SMPR; 2010

Society for Phytolith Research GEFACS

The most frequent species associated with aquatichabitats in Argentina belong to Typhaceae,Cyperaceae, Juncaceae, Apiaceae and Polygonaceaefamilies, and certain species of Poaceae, amongothers. Cyperaceae, along with Poaceae, are themain silica producers in plant kingdom. However,the phytolith production of these characteristicaquatic habitat families is scarcely known. Theknowledge of their qualitative and quantitativephytolith production would allow the identificationof these plant communities as well as particularpalaeoenvironmental characteristics in the fossilphytolith records. In order to describe the phytolithassemblages of some of the main species growing inponds, lagoons and/or aquatic habitats from SEBuenos Aires province (Argentina) we selectedthirteen species. Eight families were represented:Amaranthaceae (1 sp.), Apiaceae (1 sp.), Asteraceae(2 spp.), Juncaceae (4 spp.), Onagraceae (1 sp.),Polygonaceae (2 spp.), Solanaceae (1 sp.) andTyphaceae (1 sp.). Phytoliths from leaves wereextracted following a calcination technique andsilica content was calculated as dry weightpercentage. Juncus spp., Solanum glaucophyllum,Bidens laevis and Mikania parodii producedabundant and diverse morphotypes. The rest of thespecies produced very scarce (such as Ludwigiapeploides, Polygonum hydropiperoides,Alternanthera philoxeroides,) or did not produceidentificable phytoliths (such as Typha latifolia,Rumex crispus, Hydrocotyle sp.). Silica contentranged between 0.23 (Juncus sp.) to 2.71%(Mikania parodii). Articulated and isolatedcylindrical sulcate tracheid phytoliths andparallelepipedal psilate phytoliths, probably derivedfrom epidermal tissue, were the only morphotypesobserved in the species with scarce production.Phytolith assemblages of the species with abundantproduction were characterized by cylindrical sulcatetracheids, stomatal complexes, elongate psilatephytoliths (Juncus spp.), tabular lobate epidermalcells (B. laevis), parallelepipedal psilate epidermalcells (S. glaucophyllum, M. parodii), silica skeletonscomposed by isodiametric cells (S. glaucophyllum),silicifications of multicelullar hairs (M. parodii andB. laevis) and silica skeletons composed by diversemorphotypes.