The provinces of Santa Fe, Cordoba and Santiago del Estero are only partially wooded; large areas of plains are intermingled with scrubby forests of algarrobo (Prosopis), quebracho-blanco (Aspido-sperma quebracho), tala (Celtis tala, Sellowiana, acuminata), acacias and other genera.
We have wild olive, species of rock-rose, wild privet, acacias and mimosas, barberry and Zizyphus; and in the eastern ramifications of the chain, Chamaerops humilis (which is applied to a variety of useful purposes), Bignonia or trumpet flower, sissu, Salvadora persica, verbena, acanthus, varieties of Gesnerae.
Thickets and small acacias dot the steppes, which, green during the kharif or rainy season, at other times present a dull brown burnt-up aspect.
Only the multitude of small gardens, planted with limes, acacias and lilacs, and the bright costumes of the Servian or Hungarian peasants, remain to distinguish it from a western capital.
In those parts of the desert which have a hard level soil of clay, a few stunted mimosas, acacias and other shrubs are produced, together with rue, various bitter and aromatic plants, and occasionally tufts of grass.
In the south the red gum acacias (talh) are abundant.
Vegetation is, however, tolerably abundant - tamarisks, oleanders, kafas, euphorbias, the milk bush, rhamnus and acacias being the most common and most characteristic forms of vegetable life, and pools of water are frequent.
The flora has also some Australian and New Zealand affinities (resembling in this respect the New Caledonia and New Hebrides groups), shown especially in these western districts by the Pandanus, by certain acacias and others.
The most dominant order in Australia is Leguminosae, including the acacias with leaf-like phyllodes (absent in New Zealand).
In some cases leaves, as in Iris, or leaf-like petioles, as in Australian acacias and eucalypti, have their plane of expansion parallel to the axis of the shoot, there is then no distinction into an upper and a lower face, but the two sides are developed alike; or the leaf may have a cylindrical or polyhedral form, as in mesembryanthemum.