EXPLANATION OF PLATE XIII. 



HIEROCHLOE. — (1) A spikelet of H. borealis, enlarged; (2) the same dis- 

 played, the flowers separated from the empty glumes, the two lateral ones 

 with 3 stameus and no pistil, the middle or terminal one with a pistil and 

 only 2 stamens. 



AKTHOXANTHUM. — (1) The spike-like inflorescence of A. odoratum; 



(2) a spikelet magnified ; (3) anotlier with the parts displayed, the flowers 

 raised from the lower empty glumes, the lateral glumes empty and awned, 

 the terminal flower perfect and diandrous. 



PHALARIS. — (1) A spikelet of P. arundinacea, enlarged, (2) the empty 

 glumes, and a perfect flower with a hairy rudiment on each side of it. 



MILIUM. — (1) Portion of the panicle of M. effusum; (2) a closed spikelet, 

 magnified; and (3) the same displayed. 



AMPHICARPU:\I. — (1) A spikelet from the panicle of A. Purshii, magni- 

 fied; (2) the same, with the parts displayed; and (3) a radical (fertile) 

 spikelet, enlarged. 



PASFALUM. — (1) Inflorescence of P. laive; (2) a closed spikelet, enlarged; 



(3) the same with tlie parts displayed. 



PAXICUM. — (1) Part of a spike of P. sanguinale; (2) one of its spikelets, 

 magnified ; (3) the same with its parts displayed, the three lower glumes 

 empty. — (4) A spikelet of P. capillare, magnified ; (5) the same displayed, 

 the three lower glumes empty, — (6) A spikelet of P. claudestinum, mag- 

 nified; (7) the same displayed, the lower flower represented by a glume 

 and palet only. — (8) A spikelet of P. virgatum, magnified; (9) the same 

 displayed, the lower flower staminate. 



SETARIA. — (1) A magnified spikelet of 8. glauca, with the accompanying 

 cluster of bristles; (2) tlie spikelet displayed, showing the neutral lower 

 flower, of a glume and palet only, and the perfect flower. 



