CONTRIBUTIONS FROM THE GRAY HERBARIUM OF HARVARD 

 UNIVERSITY, NEW SERIES, No. XIV. 



By J. M. Greenman. 



Presented by B. L. Robiusou, April 13, 1898. 



L — REVISION OF THE MEXICAN AND CENTRAL AMER- 

 ICAN SPECIES OF GALIUM AND RELBUNIUM. 



A PRELIMINARY study of the Mexican and Central American species 

 of Galium has made it necessary to take into consideration the North 

 American representatives of the nearly allied genus Relbanium. The 

 latter, although not so numerously represented in Mexico, increases south- 

 ward and attains its maximum in South Ainerica, where it to a consid- 

 eiable extent replaces the genus Galium. 



Relbunium was first so designated by Eudlicher,^ as a section under 

 Galium. Subsequently it was taken up by Bentham and Hooker,"^ and 

 established as a genus ; a similar view being held by Schumann^ and by 

 Hemsley,* while Dr. Gray in t'le Synoptical Flora placed the North 

 American representatives of Relbunium under Galium. 



The typical Relbunium, however, is so well marked by its involucrate 

 flowers and distinctly axillary inflorescence, that it has seemed best to the 

 writer in the following synoptic revision to follow essentially the generic 

 limitations laid down by Bentham and Hooker, and by Schumann in 

 Enijler and Prantl's Nat. PHanzenfamilien. 



It may be added that in the examination of a large number of speci- 

 mens no difftculty whatever was experienced in placing a given speci- 

 men definitely either in one genus or in the other, except in the case of 

 G. angulosum. This species is somewhat intermediate between the two 

 genera, but a close examination of the inflorescence seems to indicate its 

 affinity with Galium- rather than with Relbunium. 



1 Gen. PI. 523. 2 Qen. ii. 149. 



3 Fl. Bnis. vi. pt. 6, 103; Engl. & Prantl, Nat. Pflanzenf. iv. Ab. 4, 154. 



4 Biol. Cent.-Am. Bot. ii. 62. 



