EXPLANATION OF THE PLATES. 



fcRACHYELYTRUM. A spikelet of B. aristatum enlarged (1) ; the same displayed (2). 

 CALAMAGROSTIS. An open spikelet of C. Canadensis, enlarged, displaying all the parts (I) ; 



the same with the flower raised out of the glumes, showing the hairy rudiment behind 



the upper palea (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 squarnulss or hypogynoua 

 scales, which here nearly equal the palese in length. 



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



ARISTIDA. A spikelet of A. purpurascens, enlarged. 



TAB. III. 



SPARTIN A. Portion of the inflorescence of S. stricta, of the natural size (1) ; a spikelet en 

 larged (2) -, and the same displayed, the flower raised above the glumes (3). 



CTENIUM. Spike of C. Americanrum (1) ; a single spikelet magnified (2) ; and the same dis- 

 played, the glumes separated (3). 



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

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



GYMNOPOGON. Inflorescence of G. racemosus, reduced in size (1) ; and a magnified spikelet 

 . with the parts displayed (2). 



CYNODON. Inflorescence, of digitate spikes (1 j a spikelet magnified and displayed, show- 

 ing a perfect flower and a rudiment (2). 



DACTYLOCTENIUM. Inflorescence of D. .ffigyptiacum, of digitate spikes (1); one of the 

 spikelets magnified (2) , the fruit magnified (3), showing the seed loose in the thin peri- 

 carp (utricle) ; and (4) the wrinkled seed more magnified. 



ELEUSINE. One of the spikes from the digitate inflorescence of E. Indica (1) ; a magnified 

 spikelet (2) ; the same with the flowers more displayed (3) ; a flower from the last show- 

 ing its parts (4) ; the fruit magnified, showing the seed loose in the utricle (5) ; and the 

 wrinkled seed detached (6). 



LEPTOCHLOA. Small portion of the inflorescence of L. fascicularis (1) 5 one of its spikelets 

 displayed and magnified (2; ; an open flower of the same (3). 



TAB. IV. 



TRICUSPIS. Magnified spikelet of T. seslerioides (1) , the same displayed and the lowest 

 flower open (2) ; back view of the lower palese spread out (3). -* 



DUPONTIA, or, as it should be, GRAPHEPHORUM (see Addenda, p. c.). A magnified spike- 

 let of Dupontia Cooleyi or Graphephorum melicoides, displayed (1) ; a part of the hairy 

 rhachis and one flower of the same (2). 



DIARRHENA. A spikelet of D. Americana, enlarged (1) : the grain and palese (2). 



DACTYLIS. A spikelet of D. glomerata magnified and displayed. 



KGELERIA. A magnified spikelet of K. cristata, expanded, showing the glumes, the three 

 flowers, and a rudiment (1) ; lower half of a lower palea, partly spread open (2) ; it is 

 much more folded and keeled in its natural condition. 



EATONIA. A magnified spikelet of E. obtusata, expanded, showing the glumes, the two flow- 

 ers, and a rudiment. 



