162 CLASSIFICATION OF [CH. 



Agrostis canina, L., is somewhat larger than A. alba. 

 Palea (only one present, sometimes minute) punctate, 

 2 mm., with a fine dorsal awn a little longer than the 

 palea. Caryopsis 12 mm. Rachilla obsolete. 



The awn is usually absent from A. alba and its varieties ; and 

 when present is so small as to be almost negligible. 



A. canina is easily distinguished from Poa by the rachilla in the 

 latter, and absence of awn. Aira has basal hairs, &c. 



Agrostis setacea, Curt., has the awn basal and just 

 projecting beyond the pointed glumes, and the palea 

 very minute, with a few silky hairs below. 



Agrostis Spica-venti, L. (Fig. 49). 



Palfea 2'4 mm. long, with infolded edges and punctate ; 

 a minute rachilla at its base, and a slender awn, 8 — 9 mm. 

 or more long, inserted below the bifid tip. Caryopsis 

 I'omm. A few silky hairs at the base of the palea. 



(6) Awn terminal or slightly sub-terminal, and 

 straight, or at least not twisted or " kneed." 



(1) Palece so closely adherent to the fruit that 

 the terminal awn appears to come from 

 the latter [Barley type]. The three florets 

 generally coherent. 



* Awn at least tivice the length of the grain. 



Hordeum sylvaticum. 

 H. mv/rinum. 



Hordeum sylvaticum, Huds. 



Palea scabrid, ribbed above, awn at least twice as long 

 as the very narrow grain. 



