IX] " SEEDS " 141 



8 — 5 nerved and with a faint web. It is close to 

 P. pratensis. 



Poa trivialis, L. (Fig. 56). 



" Seed " 2 — 2'5 mm., and with a bluish or bronzed 

 cast. Caryopsis 1 — 1*5 mm. 



Palea acute, distinctly five-ribbed, glabrous, the margin 

 scarcely overlapping. Caryopsis grooved, blunt and more 

 tightly held in the palea. 



P. trivialis differs from P. pratensis chiefxj in tlie distinct ribs 

 and smoother palea, grooved caryopsis, and bluer hue. 



P. neynoralis, L., hardly differs from P. trivialis, but 

 the palese are sub-acute, nerves obsolete, and scarcely 

 hyaline at the margins. The " seed " is shorter and more 

 acute, and the colour less pronounced, and with hardly a 

 trace of hairs (Fig. 54). 



When the basal hairs are absent this should go with 

 P. annua, &c. (see p. 146). 



It is practically impossible to distinguish these species by the 

 " seed." Care is necessary to distinguish Koeleria, which is somewhat 

 larger in size, keeled, compressed and nerved similarly, but is more 

 pointed and cm-ved and paler yellowish white in colour. Hard and 

 devoid of web or hairs. Aira is distinguished by the awn : Agrostis 

 by the very different paleae and caryopsis. 



The other Poas are devoid of web, though they may have hairs 

 below, and require very careful examination. The whole group is 

 excessively difficult to deal with in "seed," and a special study of it 

 is needed, since several species are important, and it forms a type. 



(b) No web or pencil of hairs below the " seed." 



(1) Apex of palea rounded, blunt, notched, or at 

 most bluntly pointed, but with no trace of 

 awn- or bristle-tip. 



