144 CLASSIFICATION OF [CH. 



= = Rachilla cylindrical. 



Festuca elatior. 



This is an important grass, and should be thoroughly mastered 

 as a type of the boat-shaped " seed." 



This, with Lolium, Agropyrum, other Fescues, and even some 

 Bromes and Poas, will give trouble until the student thoroughly 

 masters the importance of the minute characters of size, nervature, 

 of the rachilla, awn, palea, &c. 



Festuca elatior, L. (var. pratensis) (Fig. 58). 



Palea ovate-lanceolate, five-nerved, slightly scabrid, 

 with a slight membranous margin and cilia, rounded 

 back, and no awn. 6 — 7 '5 mm. long. 



Caryopsis oblong-obovate, somewhat flattened, hardly 

 grooved and adhering to the palese, about 3 — 3'5 mm. 

 long. 



Rachilla cylindrical, smooth. 



The other varieties of F. elatior cannot be distinguished by the 

 " seed " alone : in my samples F. elatior proper is longer than 

 F. pratensis^ and both have occasionally a trace of awn. Yar. arun- 

 dinacea has a more acuminate, stiff point. Festuca pratensis has 

 its palea as a rule somewhat more acute than Lolium perenne, and 

 the flatter tapering rachilla of the latter is more closely appressed to 

 the palea. The caryopsis of Festuca also tends to adhere to the 

 palese. 



© ® Paleoi and "seer/" at most 3 — 3'5 mm. long. 



= Palea devoid of hairs or keel, notched or 

 hlunt, and with no trace of awn. 

 A Palea hyaline, nerves indistinct. Tips 

 notched or blunt. 



Agrostis alba. 



There is occasionally a very short basal hair (awn). 



Agrostis and Aira will present difficulties to the beginner, not 

 only on account of their small sizes, but also from the variability as 

 regards awns, basal hair-tuft, &c. None are of value, and most of 

 them are weeds. 



