Ill] VEGETATIVE CHARACTERS 53 



entire. Leaves numerous. Blades long, dark green, suc- 

 culent and scabrous : ridges numerous and flat above, but 

 distinct (Fig. 9). 



A. agrestis^ L. in S. England has shorter leaves, and ridges not 

 flattened ; it is a troublesome pest of arable land, but does not 

 usually invade pasture. 



A. geniculatus, L. is semi-aquatic, and like the last. It is easily 

 recognised by its sharply bent "knees," and is of little value (Fig. 3). 



Alopecurus shows resemblances to Lolium (see p. 49), Festuca 

 (see p. 60), and Agrostis (see p. 52). If well grown its ridged 

 sheath and leaves, the former brown or black at the base, aid in 

 distinguishing it. 



(2) Blades either devoid of ridges or with very incon- 

 spicuous ones. 



* No trace of ridges, and the mid-ribs not prominent^ 

 hut the leaves show median lines flanked by finer ones 

 when held vp. Blades thin and narrow. Somewhat 

 heeled, 



(i) Shoots compressed. 



Poa compressa, L. (Flat-stemmed Meadow-grass). 

 Leaves rather short, more or less glabrous or glaucous, 

 and V-shaped at the base ; shoots compressed, and navi- 

 culate in section. Ligule short and thin. Sheath tends 

 to be closed below. A creeping perennial on commons 

 and waste lands, and of little or no value. 



Poa annua, L. (Annual Meadow-grass). Small annual. 

 Compressed shoots, limp. Leaves linear, pale, sub-acute, 

 thin, often wavy, flat, flaccid, bright green ; dull or slightly 

 shining and V-shaped in section below. Ligule long, 

 pointed, whitish and clasping the shoot. It is a harmless 

 weed, and since it puts out shoots all the year round, 

 furnishes a certain amount of pasturage. 



