As far as New Braunfels, the Prairies are occasionally relieved by clumps of fine old trees; but below that point the traveller only encounters, and that at rare intervals, a few scarce coppices and scanty thickets. Growing more common at San Antonio de Bejar, they abound in the region of Castroville, and spread over nearly the entire country to the very borders of Mexico. These bushes or coppices mainly consist of the _Prosapis glandulosa_, the _Guaiacum angustifolium_, the _Xanthoxylum inerme_ and a few Acacias. The Guaiacum[113] is noticeable for its hard and heavy wood, generally known as _Lignum Vitæ_, sometimes as _Guaiacum wood_, and occasionally as _Brazil wood_. It also yields a peculiar resinous product, which is medicinally employed, in powder, pill, and tincture, for the relief of chronic rheumatism and chronic skin diseases. It is of a greenish-brown colour, and though it has scarcely any taste, leaves a hot arid sensation in the mouth. The _Xantoxyton_ type, of the order Xanthoxylaceæ, derives its name from the yellowness of its timber. Its fruits have a pungent aromatic taste, like pepper. The popular name of "toothache tree" is applied to some of the American species, from the relief their bark and fruits are supposed to give in cases of that distressing affliction. In the neighbourhood of Castroville, Trécul found, profusely scattered among the thickets, a species of _Ephedra_, closely resembling the _Ephedra altissima_, whose feeble reed-like branches were literally covered with small red fruits, producing a novel and attractive effect. As a plant curious from its mode of vegetation, and which is spread in Texas as well as in Louisiana, I may mention the _Tillandria usneoides_, so named after Professor Tillands, of Abo. This is a genus of _Bromeliaceæ_, growing on the boughs of trees, and notably on those of the evergreen oak. It hangs down like a tuft of long gray hair, in somewhat the same fashion as certain lichens (_usnea_) in European pine-forests, communicating to the trees a strange and positively weird aspect. The plant is collected, and the outer cellular portion being removed by soaking in water, the fibrous residuum is then employed to stuff cushions, mattresses, and pillows; whence it is sometimes called "Vegetable horse-hair." [Illustration: VEGETABLE LIFE IN THE TEXAN PRAIRIES. 1. Yucca Tréculeana. 4. Echinocactus robustus. 2. Silphium terebinthinaceum. 5. Cereus Peruvianus. 3. Mamillaria rodantha. 6. Opuntia microdasys.] In the thickets that dot the central Prairies commonly flourish the _Lantana Camara_, and the curious _Ungnandia speciosa_, a species of chestnut tree on a very reduced scale.