EXPLANATION OF THE PLATES. 699 



Genera of Gramineas or Grasses. 

 Tab. VII. 



LEERSIA. — Panicle of L. oryzoides, reduced in size (1); a branchlet of the same 

 with its spikelets, of the natural size (2); and an open spikelet in flower, en- 

 larged (3). 



ZIZANIA. — A staminate (1) and a pistillate (2) flower or spikelet of Z. aquatica; 

 a magnified pistil with a pair of squamulaa or hypogynous scales (3); a grain 

 (4); and a magnified longitudinal section of the lower part of the same, show-, 

 ing the embryo at the outside of the base of the albumen. 



ALOPECURUS. — Part of a plant of A. genicnlatus, in flower (1) ; a few spikelets 

 from the spike-like inflorescence, moderately magnified (2); an open spikelet 

 in flower, more magnified (3), and the single lower palet detached (4). 



PHLEUM. — A detached spikelet of P. pratense, having the flower with its palets 

 raised above the glumes, magnified. 



CRYPSIS. — Inflorescence (1) of C. schoenoides; a separate enlarged spikelet (2); 

 and the same open, in flower (3). 



VILFA. — An enlarged spikelet of V. vaginsefiora (1); and the same displayed (2). 



SPOROBOLUS. — A spikelet of S. cryptandrus, magnified (1); the same with the 



flower open, the palets raised above the glumes (2); and the fruit (3), more 



magnified, showing the seed loose in the pericarp (utricle). 

 AGROSTIS. — Panicle of A. vulgaris (1); with an enlarged open spikelet of the 



same: also (3) the rough pedicel and glumes of A. scabra, with the flower 



separated, the latter having no upper palet. 



Tab. VIII. 



POLYPOGON. — Spike-like contracted panicle of P. Monspeliensis (1); an enlarged 

 detached spikelet, showing the long awns to the glumes (2); the same open 

 in flower (3); and a separate flower without the glumes (4). 



CINNA. — A magnified spikelet of C. arundinacea (1); and the same open, display- 

 ing the palets, the single stamen, and the pistil (2). 



MUHLENBERGIA. — A magnified closed spikelet of M. sylvatica (1); the same 

 with the open flower raised out of the glumes (2). A magnified spikelet of 

 M. diffusa (3); its minute and unequal glumes more magnified (4); and an 

 open spikelet of the same (5). 



BRACHYELYTRUM. — A spikelet of B. aristatum enlarged (1); the same dis- 

 played (2). 



CALAM AGROSTIS. — An open spikelet of C. Canadensis, enlarged, displaying all 

 the parts (1); the same with the flower raised out of the glumes, showing the 

 hairy rudiment behind the upper palet (2). 



ORYZOPSIS. — An open magnified spikelet of 0. asperifolia (1); and the flower of 

 the same removed from the glumes (2). Notice the remarkably long squa- 

 mulse or hypogynous scales, which here nearly equal the palets in length. 



STIPA. — Glumes and flower (a little separated) of S. avenacea, enlarged. 



ARISTIDA. — A spikelet of A. purpurascens, enlarged. 



Tab. IX. 



SPARTINA. — Portion of the inflorescence of S. stricta, of the natural size (1); a 

 spikelet enlarged (2); and the same displayed, the flower raised above the 

 glumes (3). 



CTENIUM. — Spike of C. Americanum (1); a single spikelet magnified (2); and the 

 same displayed, the glumes separated (3). 



BOUTELOUA. — A portion of the compound spike, of the natural size (1); and a 

 spikelet displayed and magnified (2), the flowers raised out of the glumes. 



