The flora in Los Glaciares National Park is that typical to the Andean Patagonian wood, and is found throughout the steppes and forests surrounding the Park, over a surface of approximately 79,000 has.

Some 260,000 has of the Park are ice-covered and therefore bare of vegetation, and another 95,000 has are occupied by lakes.

Over all the forested areas there is a prevalence of lenga and coihue trees. The bushes are mainly notro, with its beautiful red flowers, calafate, with yellow flowers and purple fruit, and the sauco del diablo, in the more humid areas of the forest.

It is worth noting that the woods in the Viedma Lake area have been studied much less than those of the Argentino Lake area. Lenga forests are more common here, and generally do not form uninterrupted belts, alternating with patches of steppe-like vegetation.

The thicker and more uniformly forested areas are found in the western valleys, whereas the steppes are seen in the east.

There are three well-defined types of vegetation:

The Forest
Below the high-Andean flora, and down to the level of the lakes, the nothofagus forests are found. The upper limit of the forest is at around 1,000 to 1,100 m altitude. There are three nothofagus species in the Park:

Lenga (Nothofagus pumilio).

ire (Nothofagus antrctica).

Coihue or Guindo (Nothofagus betuloides).

Of the three, the lenga is the most widespread and occupies the greater part of the woods in the area. This tree is usually found covered with usnea (a lchen), usually known as "old man's beard" due to its form of long untidy strands hanging from the tree trunks.

The lenga, in addition to standing a wider range of temperatures, is not as sensitive to cold as the coihue. As a result, in the vicinity of glaciers, the lenga gets closer to ice. These forests, highly resistant to low temperature, also cover the bottoms of the high mountain valleys that are constantly exposed to masses of cold air.

One species of creeper, luzuriaga marginata, is usually found on river banks or at the base of trees. Philesia magallnica, on the other part, is a very unusual tree creeper with nice red flowers.

As from 500 m altitude, the forest thins out, with specimens turning stunted and scrawnier. The sauco and the cinnamon tree disappear, together with several low-forest species, and the lengas replace them. The coihue is found in bush form up to approximately 850-900 m, while the lenga continues to be found in low heath up to around 1,000 m.

In the herbaceous strata we find ferns, mosses, lichens and flowers such as the shoe-shaped topa-topa, and orchids.
Blue-flowered sweet peas heavily cover the surfaces surrounding the glaciers. There is also a unique species, pinguicula antrtica, with violet flowers. This is an insectivorous plant that traps and eats its prey to obtain the nitrogen compounds it needs for growth.

Among the forests on the eastern border of the Canal de los Tmpanos (Iceberg Channel), there is a clear difference between pure lenga forests and those having both lenga and coihue.

The ire, although it is found much more rarely found than the lenga, is fairly common in valley bottoms.

The Steppe
The steppe vegetation growing around Los Glaciares National Park is uniquely adapted to highly arid, cold and windy conditions. The grasses in the area, whose leaves are creased, rigid and "thick-skinned", make low, thick mattocks, which form circular tussocks, as in the case of the neneo.

In the lowest eastern areas, the steppes are covered with coirn amargo (Stipa app.) and low bushes.

Among bush species, the most often found are Senecio filaginoides and Berberis buxifolia, and the commonest herbaceous species are Festuca Argentina, Poa lanuginose and/or Poa dusenii, accompanied by some forage species.

The High Semi-Desert
This vegetation type is found at over 1,000/1,100 m altitude, up to 1,500/1600 m, this being the lower limit of the permanent snow.

There is little vegetation cover here. However, there is a predominance of tussocks of xerophytes and dicotyiledons; among the latter, the most ordinarly are tussocks of genus Azorella and Bolax.

In the wet areas, there are small densely-populated meadows with abundant Azorella lycopodioides, Epilobium australe, Epilobium nivale, and Alopecurus antarcticus, among other species; often with Empetrum rubrum and Marsippospermum cf reichei.

In some sites, immediately above the level of the bush-type lengas, there is a more-or-less dense bushy stratum with a predominance of Empetrum rubrum and Pernettya sp.

In contrast with the North Patagonian high-Andean vegetation types, many species of Mulinum are absent, whereas many sub-Antarctic specimens are to be found.