CONTRIBUTIONS FROM THE GRAY HERBARIUM OF HARVARD 
UNIVERSITY, NEW SERIES, No. XIV. 
By J. M. Greenman. 
Presented by B. L. Robinson, April 13, 1898. 
I.— 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 Relbunium. The 
latter, although not so numerously represented in Mexico, increases south- 
ward and attains its maximum in South America, where it to a consid- 
erable extent replaces the genus Galium. 
Relbunium was first so designated by Endlicher,’ 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 the 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 
Engler and Prantl’s Nat. Pflanzenfamilien. : 
It may be added that in the examination of a large number of speci- 
mens no difficulty whatever was experienced in placing a given speci- 
men definitely either in one genus or in the other, except in the case of 
- angulosum. This species is somewhat intermediate between the two 
senera, but a close examination of the inflorescence seems to indicate its 
. 
allinity with Galium rather than with Relbuwnium. 
ei 
1 Gen. Pl. 523. 2 Gen. ii. 149. 
8 Fl. Bras. vi. pt. 6, 103; Engl. & Prantl, Nat. Pflanzenf. iv. Ab. 4, 154. 
* Biol. Cent.-Am. Bot. ii. 
