The pampas, which cover so large a part of the republic, have no native trees whatever, and no woods except the scrubby growth of the delta islands of the Parana., and a fringe of low thorn-bushes along the Atlantic coast south to Mar Chiquita and south of the Tandil sierra, which, strictly speaking, does not belong to this region.
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.
On the upper verge of the pine forests, or in the scrubby vegetation just beyond, the following are not uncommon - black woodpecker (Picus martius), ring-ousel (Turdus torquatus), Bonelli's warbler (Phylloscopus Bonellii), crested tit (Parus cristatus), citril finch (Citrinella alpina), siskin (Chrysomitris spinus), crossbill (Loxia curvirostra), nutcracker (Nucifraga caryocatactes), blackcock (Tetrao tetrix), and the alpine varieties of the marsh-tit (Parus palustris, borealis) and tree-creeper (Certhia familiaris, costae).
The surface of the plateau is generally open campo and scrubby arboreal growth called caatingas, but the streams are generally bordered with forest, especially in the deeper valleys.
The vegetation consists almost entirely of scrubby bushes of several varieties, including tamarisks and wild briers, of reeds (kamish), and of grass on the yaylaks (pasture-grounds) of the middle ranges.
The plateau, known as the Ogaden plateau, everywhere presents the same monotonous aspect of a boundless steppe clothed with a scanty vegetation of scrubby plants and herbaceous growths.
There is but little natural vegetation to be seen - ragged yucca trees, many species of agave and cactus, scrubby mesquite bushes, sage bushes and occasional clumps of coarse grasses.