Analysis of the patterns of distribution of photosynthetic pathways and representativity of the family Poaceae on Martin Garcia Island, Rio de La Plata, Buenos Aires, Argentina

Martin Garcia Island lies on an unique geographical location in South America where species from three different phytogeographical provinces meet. Although its surface area is very small (168 hectares), it has a wide variety of vegetation types ranging from gallery forests to xerophytic woods. The floristic inventory of this island was updated for the family Poaceae by collecting and identifying material with an outcome of 118 taxa, 32 of which are cited for the first time for the area. The plants collected were classified according to their tribe, subfamily, genus, species and photosynthetic pathway. The distribution of the photosynthetic types C3/C4 in the various ecological units of Martin Garcia Island was discussed on the basis of sun/shade and humidity parameters. The results show that C3 taxa prevail in humid and shady habitats and C4 taxa in dry and sunny areas.