I] 



SHOOTS AND NODES 



15 



often found at the base of the sheaths themselves over 

 these : the latter are often conspicuous when the 

 former are inconspicuous — e.g. 

 most species of Agrostis, Avena, 

 Festuca, &c. 



The nodes are of importance 

 in the description of a few species 

 only — e.g. they are usually dark 

 coloured in certain Poas such as 

 P. compressa and P nemoralis; 

 they are sharply bent in Alope- 

 curus geniculatus, and may be so 

 in other species if " layed " by 

 wind, rank growth, &c. 



A point of considerable classi- 

 ficatory value is the shape of the 

 transverse section of the shoot, 

 which is correlated with the mode 

 of folding up of the young leaf- 

 blades. 



In most grasses the blades are 

 convolute — i.e. rolled up like the 

 paper of a cigarette, one edge 

 over the other — and the section 

 of the shoot is round (Fig. 7). 

 In some cases, however, the leaves are conduplicate — i.e. 

 each half of the lamina is folded flat on the other, the 

 upper sides being turned face to face inwards, with the 

 mid-rib as the hinge — and in this case the shoots are more 

 or less compressed (Fig. 6). 



Fig. 5. Cynodon Dactylon. 

 Plant (reduced) showing 

 creeping and stolonifer- 

 ous habit, and peculiar 

 inflorescence of digitate 

 spikes. Parnell. 



