Studies in the Asclepiadaceae—VI, Notes on the Genus Rouliniella 
By ANNA MURRAY VAiL 
A close examination of herbarium specimens variously labelled 
Roulinia Jacquinii, R. unifaria and R. racemosa show that there 
are several species which if not new are at least deserving of rec- 
ognition; and this is an attempt to straighten out some of the 
species of a most interesting little genus. 
About twenty-one or twenty-two species can be enumerated, 
ranging from Texas to Argentina; but as the genus is but poorly 
represented, even in foreign herbaria, it is difficult without careful 
dissection to determine whether all the species credited to Roulinia 
are correctly placed. 
Rouliniella 
Roulinia Decne.; D. C. Prod. 8: 516. 1844; Schumann, 
Die nat. Pflanzenfam. 4?: 255. 1895. Not Brongniart, 1840. 
The seven species enumerated here all bear small flowers and 
are closely related. The available material of the South American 
species is at present too scanty to study with any kind of satisfac-_ 
tion.* 
Key to the Species 
Crown-segments not exceeding the stigma, 1. R. unifaria. 
Crown-segments barely exceeding the stigma, conspicuously 3-lobed. 2 
2. R. Columbiana. 
Crown-segments exceeding the stigma, long-ligulate. 
Flower-buds sub-globose. 
Central lobe of the’ crown-segments obscurely 3-toothed at the apex ; fone 
buds obtuse. e2 ™ 3. X- Palmert. — 
Central lobe of the crown-segments entire ; flower-buds acutish. 
Ae fs racemosa. 
-  Flower-buds ovate, acute or sub-acuminate. 
Central lobe of the crown-segments truncate at the apex. 5. %. 45” 
_ Central lobe of the crown-segments acute at the apex. 6. A foetida. 
Central lobe of the crown-segments very long and slender, undulate. 
osa. 
: 7. R. Jaliscana. — 2 
nying fi Uk cee joa. 
_ *The accompanying figures represent : 4, the bud ; ¢, the crown (diagramma! 
_ enlarged) ; /, the expanded flower, and are all magnified four diameters ; f, the ee : : 
