23 



Hartog, C. den and F. van der Plas. 1970. A synopsis of the Lemnaceae. 

 Blumea 18: 355-368. 



Hicks, L. E. 1932. Flower production in the Lemnaceae. Ohio J. Sci. 32: 

 115-131. 



Jacobs, D. L. 1947. An ecological life history of Spirodela polyrhiza. 

 Ecol. Monog. 17: 437-469. 



Landolt, E. 1980. Key to determination of taxa within the family of 

 Lemnaceae. In: Landolt, E. (ed.). Biosystematic investigations in 

 the family of duckweeds (Lemnaceae). Veroff. Geobot. Inst. ETH 

 Stiftund Rubel, Zurich 70: 13-21. 



McClure, J. M. and R. E. Alston. 1966. A chemotaxonomic study of 

 Lemnaceae. Amer. J. Bot. 53: 849-860. 



Saeger, A. 1929. The flowering of Lemnaceae. Bull. Torr. Bot. Club 56: 

 351-358. 



Thompson, C. H. 1898. A revision of the Lemnaceae occurring north of 

 Mexico. Annual Rept. Missouri Bot. Gard. 9: 21-42. 



Urbanska-Worythiewicz, K. 1975. Cytological variation within Lemna 

 L. Aquatic Bot. 1: 377-394. 



XYRIDACEAE 



Xyris (Yellow-eyed Grass) 



Emersed plants of wet peaty or sandy soil. Perennial, growing from 

 fibrous roots; leaves basal, tufted blades linear, bases abruptly or 

 gradually dilated; flowers perfect, yellow, in the axils of leathery or 

 chaffy imbricate bracts; fruit a capsule. 



Key to Species 



1. Plants bulbous and hard at base (fig. 7A); keel of lateral sepals 

 ciliate from the apex to below the middle, with a tuft of longer hairs 

 at the apex (fig. 7C). 

 1. X torta 



1. Plants not bulbous, but soft and flattened at base (fig. 7E, 8A, 9A); 

 keel of lateral sepals non-ciliate or cilia limited to the terminal half, 

 keel with (fig. 8C, 9C) or without (fig. 7G) a terminal tuft of hairs at 

 the apex. 



