TT] 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 8. 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. 50), 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, 
but the leaves show median lines flanked by finer ones 
when held up. Blades thin and narrow. Somewhat 
keeled. 
(1) 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. 
