In addition to the expanse of the moors, most of the Armorican Massif is notable for a higher percentage of Atlantic species; and as such species are also observed, more or less, throughout the Loire basin, the Flahault was led to distinguish an Armorian-Ligerian sector. However, when you pass south of the lower Loire from the Vendée and Poitou, you are faced with new species. Certainly it is necessary to distinguish an Aquitanian sectorincluding the whole Aquitaine basin, characterized by a mixture of Atlantic species with Mediterranean species that emigrated through the Naurouze threshold. The sandy plain of the Gascony moors, extending behind the coastal dunes, forms a rather typical region, which in its natural state is covered with pines, moors with gorse and moors intersected by peat swamps, which maintain the formation of a crust in the sand ferruginous (alios). It may be that, with the deforestation, man has contributed to making their mobility to the immobilized sands, but it is certain that since the nineteenth century he has reforested immense areas regularly cultivated.
On a rather narrow coastal strip, the oceanic influence is revealed with the spread of the southern species, favored by the warmth of the autumns and the absolute lack of frost. Thus, the holm oak (Quercus ilex) which meets up to the mouth of the Loire, together with cysts and strawberry trees (Arbutus), forms dense woods in the depressions of Gascony sheltered by the dunes. Furthermore, mimosa is grown on the island of Noirmontier. In the rest of Aquitaine, Atlantic influences generally prevail, so that Mediterranean plants appear only in dry areas; and tertiary limestones, which form small causses in Ninervese and in Castrese, lead douches, Phyllireaand also holm oaks, with an aspect reminiscent of the garrigue, a word used in the plateaus of the Causses del Quercy, as well as in the granite Ségalas del Rouergue.
According to ZIPCODESEXPLORER, the true border line of the Mediterranean dominion, to the west, does not go beyond Carcassonne; it goes up to the north, following the Rhone as far as Montélimar, encompassing all of lower Provence, including the Durance, as far as Sisteron, and the Varo as far as Puget Théniers. The plant associations characteristics are the forests of cork oaks (Quercus Suber) and pine (Pinus maritima and P. Halepensis) with their undergrowth of xerophilous shrubs, often thorny and fragrant: large white heather (Erica arborea), various laurel, arbutus (Arbutus), cysts (especially Cistus monspeliensis), Phyllireaetc. On land that is too poor or cleared, undergrowth exists only in the form of maquis.
In general, the limestone soils are not capable of nourishing even the maquis ; they are the domain of the garrigue, a species of moor, whose essential element is that small oak (Quercus coccifera), which in Provençal is called garrus ; only thin groves of boxwoods and tufts of xerophilous grasses grow there. The presence of sparse forests of holm oaks in certain points of the sous – cevenols limestone plateaus supports the hypothesis that the scrub is largely an effect of deforestation. On the alluvial soils, deep and humid, in the Mediterranean domain you can see dense forests with deciduous trees (Quercus pedunculata,Fraxinus ornus, etc.) and numerous lianas. Undoubtedly, deforestation has greatly changed the characteristics of the vegetation of the Mediterranean region; the cultivation of the vine represents an important part of it, and that of the olive tree can be considered absolutely characteristic.
In the French Mediterranean domain, the Flahault distinguishes three sectors: a western one (Roussillon, Narbonese), where the Iberian species are very numerous (58), including Sarothammus catalaunicus, Cistus populifolius, Astragalus narbonensis; a central one (lower Languedoc and plain of the lower Rhone), which is less rich and less Mediterranean, due to the cold winds (mistral) and in which both Iberian and Italic species are missing; one (Maritime Provence) east of Marseille, the most typically Mediterranean, with a good number of Italic species (85), mainly with the Aleppo pine, which contends for first place with the holm oak.
The orophilic flora has fairly constant characters in the various mountains of France: everywhere there is a subalpine forest level, characterized by the mixture of beech and fir; meadows or alpine heaths lie on the rather high peaks: the limit of the forest could have been lowered by man, but in general it is lower in the lower massifs (Vosges, Massif Central), and in very extensive ranges, such as the Alps, it can be 700 meters lower on the outer chains than the high inner chains. This contrast is even more important than that due to the diversity of latitudes, as seen in this table:
Each of the different mountain ranges has special floristic characters. The siliceous Vosges differ entirely from the limestone Jura, although on both sides the shelf of the conifers is very similar. Above all, the southern Jura offers a considerable percentage of species with Mediterranean affinities, while in all the highlands of the Jura one can see mostly affinities with central Europe.
The Massif Central is distinguished by the complexity of its flora, offering an affinity with the Pyrenees in the south-west and an affinity with the Alps in the south-east; the arid plateaus of the Causses have remnants of the dominion of the steppes of Central Europe (Adonis vernalis) and the Cévennes on their lower slopes have a certain Mediterranean imprint. The Savoy Prealps differ greatly from the Provence Prealps, where the Mediterranean vegetation rises to over 1000 meters; and the same contrast exists between the western Pyrenees, which have Atlantic flora, and the eastern Pyrenees, where the Mediterranean influence is felt up to heights approaching 2000 m. and where the upper forest shelf features special conifer woods (Pinus uncinata).