The Tachigalia. 



The Leguminous myrmecophytes of the genus Tachigalia 

 comprise more than a dozen known species of trees and shrubs 

 belonging to the forest formation (hytea) of the Guianas and 

 the Amazon basin. The first species, paniculata, was described 

 by Aublet as long ago as 1775, and re-described by Tulasne in 

 1844. The former derived the generic name from the Carib 

 "tachigali," "tachi" being the term employed by the natives of 

 the Guianas and Brazil for the stinging ants of the genus Pseu- 

 domy7-ma, which regularly inhabit the swollen petioles of the 

 species of Tachigalia and the hollow branches and trunk of the 

 various species of Triplaris. Spruce (1869) was also familiar 

 with several species of Tachigalia and their ant-inhabited petioles. 

 Owing to our not finding the trees at Kartabo in bloom, Prof. 

 Bailey and I have been unable as yet to ascertain their specific 

 name. They closely resemble, however, at least in their younger 

 stages, the species described by Harms (1906) as T. formicarum 

 and figured by Ule (1907), who discovered it in Brazil (Plate I). 



I first found the Tachigalia on the Puruni Trail near the 

 Kartabo laboratory on July 22. The specimens were small and 

 slender, from a foot and a half to six or seven feet tall, with only 

 two or three to about a dozen leaves, and were growing in the 

 shade. The petioles were inhabited either by beetles or by ants 

 of the genera Azteca and Pseudomyrma. On the following day 

 Prof. Bailey found what we at first took to be a different Tachi- 

 galia on the left bank of the Cuyuni River. It was a small tree, 30 

 to 40 feet high, with denser foliage and very different leaves. Its 

 petioles were all inhabited by parts of a single huge colony of a 

 yellow Pseiidomyrma. Later, on finding more material, we 

 became convinced that both trees were merely the juvenile and 

 adult forms of the same plant, the former growing in the shade, 

 the latter in the sun. Prof. Bailey found the seedlings in various 

 stages and was able to ascertain that the seed is a peculiar 



