8 Description of the Landes of Acquitania. 
ing ; the Ophioglossum lusitanicum grows abundantly in the sands 
of Brest roads; the Phalangium bicolor, a plant of Barbary, is met 
with in the Landes of Angers and Nantes ; the Cistus hirsutus, 
Helianthemum serratum, plants of Spain, grow on the borders of 
the Loire and coast of Britany. Decandolle met with lichens, 
which had only been found in Jamaica, on trees, in the vicinity of 
Quinfer-cotentin, and the Narcissus calathinus, considered as im- 
digenous to Greece, and the east, was seen by this learned bota- 
nist on the isles of Glenaus. Bory St. Vincent found the Lobelia 
Dortmanna, considered as peculiar to the north, in the Landes of 
Anvers, and the ponds of Cazau, on the slope of the Acquitanie 
downs. 
In the descriptive botany of the Landes, we must necessarily 
distinguish between the plants growing on general sandy tracts, and 
plants which flourish only in maritime sands: thus the Scabiosa 
maritima, and Galium maritimum, are not essentially maritime ; 
Corrigiola litoralis, and the Silene bicolor, grow indifferently in 
the vicinity of the sea, or in other spots ; but the Echinophora spi- 
nosa, and the Eryngium maritimum, have deep roots, which pierce 
through the sands to the salt water, from which they cannot be 
withdrawn without affecting their growth: while other plants wan- 
der to a great distance ; thus the Salsola tragus ascends along the 
gravel of the Rhone, as far as Pierre Benite near Lyons ; the Ta- 
marix gallica, abundant on the saline marshes of the basin of Area- 
chon, is also met with between Trebes and Carcassone ; the Trig- 
lochin maritimum is met with on the borders of the pond of St. 
Julien, and Decandolle found the Cochlearia officinalis on the 
mountains of Neouvielle, (High Pyrenees,) at 1600 metres* above 
the level of the sea. We shall thus be induced to treat separately 
‘of the plants of the Landes, and those of the Downs, where the pre- 
‘gress of vegetation is also different. The first plants which come to 
adorn the surface of the bare rock, belong to the family of the pul- 
verulent lichens; the foliaceous follow them, and soon after, the 
green ferns begin to wave their flexible fronds. The passage of 
mosses to ferns is perfectly well filled up ; on the one hand, by the 
Lycopodia, with imbricated and subulated leaves, comprising a 
‘crowd of species in the first family ; on the other hand, by those © 
little Hymenophylla and rampant Trichomanes, which, in the tor- 
rid zone, cover the trunks of almost all old trees, and the surface 
‘of moist rocks, confounding themselves at first sight with the Les- 
‘iz and the Jungermanniz, with whose stems they frequently inter- 
twine. In the Landes pulverulent lichens blacken the white sands, 
‘whose motions they arrest, and are succeeded by imbricated Lyco- 
‘podia, and afterwards a few grasses, or in some places mosses and 
ferns. The Downs present no appearance of this kind ; the flower 
of some vagabond plant, or an occasional patch of bent, alone ap- 
pearing at intervals to adorn these desert regions, and enliven their 
‘sorrowful sterility. In the Landes many species of lichens assist 
* The metre is equal to 1,093,633 yards. 
