IX] "seeds" 145 



Acp'ostis alba, L. (var. stolonifera). 



Palea, enclosing the fruit 1'8 — 2 mm. long, white, 

 delicate, membranous, with a blunt notched apex and 

 three (or five) nerves : occasionally there is a fine kneed 

 basal awn, not projecting. 



The glumes may remain attached : the outer has a 

 serrulate keel, and often a violet hue. No awn. About 

 2 — 3 mm. 



Caryopsis about I'l mm. long, oblong, yellow, corn- 

 shaped, furrowed, shining through. 



A . vulgaris, L., is a variety with slightly smaller 

 fruits, no awn, and usually three nerves to the palea, 

 but they cannot be distinguished with certainty by the 

 "seed." Rachilla obsolete. 



The colour of the glumes may vary coiiisiclerably and is some- 

 times yellow. 



The absence of awn, rachilla, and basal hairs distinguishes 

 Agrostis from Aira. 



AA Palea memhranous^ ribbed, tips scarious. 



Olyceria aquatica. 

 G. Jluitans. 



Glyceria aquatica, Sm. 



Palea strongly 5 — 7 ribbed, obtuse and scarious, about 

 4 mm. long. Green with a purple cast. Caryopsis dark- 

 brown, about 2 mm. long. 



Inner palea punctate. Rachilla slender and cylindrical. 



Glyceria fliiitans, Br., is very similar, but longer 

 (6 mm.) and more slender ; the palea scabrid with 

 truncate or ragged tips, and the inner palea not punctate 

 Yellow. (Fig. 46.) 



w. 10 



