ZYGOPHYLLACE^. 123 



Florida. G. angustifolium, Engelrn., belongs to Western Texas and 

 Northern IMexico. 



Properties. All the species are remarkable for their very dense and 

 heavy, close-grained wood. Lignum Vitcc, so well known in the arts as 

 well as in medicine, is the wood of G. officinale or of G. sanctum, one or 

 both. It is the hardest and heaviest wood known (its specific gravity being 

 1.333, so that it sinks at once in water), and, owing to the diagonal cross- 

 ing of the fibres, it never splits. The officinal Gmn Guaiacum is obtain- 

 ed either by natural exudation from the living tree, or by heating the 

 wood and distilling off the resin. It is what has been termed a gum- 

 resin, of bitter and acrid stimulant properties, and has long been famous in 

 medicine as an alterative and sudorific, &c. The foliage is employed in 

 the West Indies instead of soap, to scour and whiten floors. 



Division. The true species of Guaiacum have the filaments entirely na- 

 ked : but in the Zygophyllum arboreum of Jacquin, referred to this genus by 

 De Candolle, and the recently characterized G. angustifolium, jEn^'-e/m.,* they 

 are appendiculate with a small scale ! These species, being somewhat pe- 

 culiar in habit and foliage, may be separated as a genus ; but the other floral 

 characters accord so completely with Guaiacum that it seems more proper to 

 distinguish them only as a subgenus, although the presence or absence of 

 these appendages is taken to be of generic importance in this family. Their 

 cotyledons are placed contrary to the axis, while those of Porliera, Ruiz 4" 

 Pav., as figured by A dr. de Jussieu, are parallel with it, like those of Lar- 

 rea. — G. sanctum (often confounded with G. officinale), here figured for 

 comparison, is not found within the strict geographical limits of this work. 

 G. angustifolium, Engehn., is here figured partly from Lindheimer's Texan 

 specimens, but principally from a Northern Mexican specimen of Dr. Gregg's 

 collection, which furnished mature fruit, f 



PLATE 148. Guaiacum sanctum, Linn.; — a flowering branch, of the 

 natural size, from Key West. 



1 . Diagram of the flower. 



2. External view of a stamen, magnified. 



3. The same, seen from the inner side. 



4. Magnified vertical section of the pistil, &c., with two stamens. 



5. An ovule detached and more magnified. 



6. Immature fruit, enlarged. (Ripe fruit not seen.) 



* In Wislizenus's Memnir of a Tour to JVort/ieni Mexico, (Senate Document, 

 1848,) Botanical Appendix, p. 11:3. 



t Specimens in fine fruit, gutliered in Soutliern Texas, have just reached nie, 

 from Mr. Wrijrht. 



