149 



growth visible under the high power microscope, 



I Pores (tranaverse seation) very numerous and small 

 (about ,05 mm. in diameter), round when isolated, open in 

 sapwood, closed with conspicuous yellowish green tyloses 

 in the heartwood and arraiiged singly, in pairs or in small 

 groups of 3 to 4. Vessel walls (longitudinal section) with 

 numerous relatively large bordered pits. Perforations 

 simple, v/ood fibers about 1.48 mm. long, with very thick 

 walls and nearly obliterated lumina, and with minute, slit- 

 like simple pits, rt'ood parenchyma strongly developed and 

 grouped around vessels and in short irregular tangential wavy 

 lines, iJll pores are surrounded by these elements. Hays 

 very numerous and inconspicuous, barely visible with a hand 

 lens on transversa section, from 1 to 2 cells wide and from 

 6 to 8 cells high.) 



/ 

 Distribution, common names and uses 



The Panama Guayacan is known thus far from the eastern- 

 most boundary of Panama and Guatemala, growing principally 

 on the dry foothills at some distance from the Pacific Coast, 

 and never much above 300 meters of altitude. The only part 

 of the Isthmus where it is known to grow on the Atlantic 

 side of the continental divide is in the Chagres 3asin, 

 where the depression in the mountains is so deep as to allow 

 full sweep to the monsoon winds, and the penetration to the 

 north of the semi-arid climate of the southern coast. In 

 Guatemala, however, it appears again on the Atlantic water- 

 shed in the semi-arid Alta-Verapaz , ihile in Mexico, it 

 reaches as far as the iitates of Guerrero and i»IiGhoacan, 

 again on the Pacific coast, 



(The native name Guayacan , is applied to species of two 

 very distinct genera, a fact that has originated a very 

 unfortunate confusion. It is, in the first place, the ori- 

 gin of the generic name Gua jacum , applied to Zygophyllaceous 

 trees, the wood of which has been long known as Lignum vi - 

 tae , the typical Guayacdn being Gua jacum officinale from 

 Venezuela, while again the Guayac6n polvillo of Colombia is 

 also a species of Tecoma, 



) 



The Guayacan of Panama and Costa iiica, as well as the 

 Guayacdn polvillo of Colombia on the other hand, are iigno- 



