XIV. 
GENERAL NOTES. 
I, ON THE CHARACTER OF THE VEGETATION OF SOUTHWESTERN TEXAS,* 
From THE PROCEEDINGS OF THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF ScrEeNcE, Von. V. 1851. 
THE Flora of the immense territory of the United States bears a peculiar common char- [223] 
acter, distinguishing it from other regions of vegetation. This character consists in the 
prevalence of some families and more especially ‘of the Composite, of the occurrence of others 
only in this part of the globe (e. g. Magnoliace), and in the great number of species of many genera 
known in other countries only ‘i afew living representatives or among the fossil remains of the 
brown coal (tertiary) formation, Such genera are the oaks, the pines, the horse-chestnuts or buck- 
eyes, the maples, the grapevines (Vitis), the birches, the walnuts and hickories. The magnolia, the 
Gleditschiz, and the sweet gum (Liguidambar) are in Europe only found among the fossils. Herba- 
ceous plants exemplifying this character are the asters, Solidago, Helianthus, Asclepias, ete, 
But as we may naturally infer, this large territory shows different regions of vegetation, pro- 
duced or influenced by climate, conformation of the surface, geological character of the soil, and 
perhaps other causes not so readily appreciable. 
Such different areas are the northeastern Alleghanies and their slope to the Atlantic; the 
southern part of that mountain range and its eastern slope to the ocean; the subtropical region of 
Florida, so different from that of Texas though in the same latitude; then the western slope of the 
Alleghanies towards the immediate valley of the Mississippi; the northern and the southern part of 
that valley itself, the latter including Northeastern Texas; again the region of the Western plains 
and deserts; that of the Rocky Mountains, of the Pacific coast, and finally the peculiar flora of 
Southern Texas, or of the Rio Grande v: i 
Though I have never explored that country myself, the extensive and beautiful collections of 
my friend Ferdinand Lindheimer, together with his very full notes, enable me to attempt a sketch 
of the character of that flora. 
And I here take the liberty of again reminding you of a remark made from this place a day or 
two ago by one of our highest authorities, in speaking of paleontological collections, and which can- 
not be too often repeated and inculcated; that is, it is not only the collected specimen itself, which 
is valuable, but the notes, the data in regard to exact locality, association with other forms, 
and all circumstances tending to enlighten us in regard to it, are absolutely necessary to give [224] 
to the specimen its full value. 
Southwestern Texas, as I regard it, to judge by the character of its vegetation, has its natural 
boundaries to the northeast on the Brazos, or more properly between this and the Colorado River; 
to the southeast in the alluvial plains which extend from the Gulf coast into the interior, and 
which bear more the character of a subtropical vegetation; to the south and southwest by the Rio 
* See also an account of the western part of Texas in Boston Journal of Natural History, vol. vi. 1857, pp. 34-40. — Eps. 
67 
