EXPLANATION OF PLATE IV. 



DICHROMENA. (1) Head and involucre of I), latifolia ; (2) a scale 

 from one of the spikelets, and (3) the same cut across; (4) a flower; 

 (5) achene with its tubercle. 



PSILUCARYA. (1) Part of plant, (2) enlarged spikelet, (3) detached scale, 

 (4) flower, and (5) achene with its beak, of P. scirpoides. 



RHYNCHOSPORA. (1) Upper part of flowering stem of R. Torreyana ; 

 (2) a spikelet; (3) detached flower; (4) achene, with short bristles at 

 its base ; (5) one of these bristles more magnified. 



R. ( CERATOSCHCENUS). (1) Upper part of fruiting plant, (2) de- 

 tached spikelet, (3) flower, and (4) beaked acheue, with its bristles, of R. 

 macrostachya. 



