NOTES ON GROUP XII. 



1. Thick-bladed Poas. The blade may be recog- 

 nised as thick by holding it up to the light ; a dark 

 green appearance means thickness ; a light green, thin- 

 ness. Thickness may also be recognised by the firm 

 feel between the fingers. 



2. Thin-bladed Poas. Recognised by the light- 

 green colour of the blade, when held up to the light, 

 and by the softness between the fingers. 



ou ^u a 4. f Edges rounded annua. 

 Sheath flat, < T?J * ' i- 



' ( Edges acute tnviahs. 



This character is best observed by cutting a shoot and 

 examining the section under the lens. 



Poa annua. This is recognised as annual by 

 teasing out the shoots, and observing that 

 they all contain flowers. 



Poafertilis. Is being introduced into cultiva- 

 tion, and for this reason it is included. 



Poa bulbosa. Is dry rather than soft-bladed. 

 Among bulbous grasses, and those with ex- 

 tensively creeping underground stems, the 

 blades tend to thinness and dryness, or hard- 

 ness e.g., Avena elatior, Triticum repens, 

 Poa pratensis, &c. 



3. Dry-b laded Avena species. 



Avena elatior has also dry blades ; the ribs are 

 low and very flat ; there are no median lines. 



Avcnaflavescens\&& thin and softer blades ; the ribs, 

 thoughlow,areacute; there are no median lines. 



4. Triodia decumbens. Superficially examined, the 

 blade might be regarded as that of a thick-bladed Poa, 

 inasmuch as the median lines are very conspicuous. 

 The pressure of low and very flat ribs suffice to dis- 

 tinguish it. This is the only grass with a flat sheath, 

 and ligule a tuft of hair. 



5. All Poas have keeled blades, except maritima. 

 (VIII. contd., 15.) 



