[1] The largest block has a V shape, covering the foothills and lower valleys of the Eastern Ranges and the Mérida Andes, which extend to the north and east respectively.

[1] The portion of the ecoregion to the south and west of Lake Maracaibo is viewed as a Pleistocene refugium for woody plant families, and is the only area north of the Andes still holding remnants of Brazil and Colombia's Amazonian flora.

The upper canopy at about 40 metres (130 ft) includes Anacardium excelsum, Carapa guianensis, Ceiba pentandra, Coumarouna punctata, Couroupita guianenesis, Eschweilera species and Sterculia apetala.

The middle canopy at about 20 metres (66 ft) contains Calophllum brasiliense, Guarea thichioides, Parkia pendula, Pentaclethra macrobola and Swartzia species.

Other flora include Gustavia hexapetala, Cariniana pyriformis, Faramea capillipes, Ochoterenaea colombiana, Miconia mocquerysii and Vochysia lehmannii.

In the western and southern parts of the ecoregion, which has been degraded by logging, agriculture and livestock grazing, there is secondary growth of the genera Casearia, Cecropia, Croton, Inga, Isertia, Jacaranda, Trema and Vismia.

[2] Isolated species along the Onia River include Faramea capillipes associated with other lowland tropical forest species such as Tapirira guianensis, Diplasis karataefolia, Maprounea guianensi, Olyra micrantha, Leandra solenifera, Miconia barbinervis, Miconia nervosa, Mouriri myrtifolia, Abuta pahni and Psychotria capitata inudata.

Relict plant species in Catatumbo and eastern Colombia include Ochoterineae colombiana, Miconia mocquerysii, Palicourea buntingii and Vochysia lehmannii.

The brown hairy dwarf porcupine (Coendou vestitus), a very rare mammal, lives in warm lowlands up to elevations of about 2,600 metres (8,500 ft).

[2] Endangered mammals include Geoffroy's spider monkey (Ateles geoffroyi), red-crested tree-rat (Santamartamys rufodorsalis) and woodland Oldfield mouse (Thomasomys hylophilus).