"TTT" EST a a ENEMY 
OF THE LEAVES OF BRITISH GRASSES. 349 
The mechanical tissue is never very scanty, in most cases it is fairly abundant; 
generally forms girders or moderately strong bands above and below, at least, the ER 
vascular bundles. There is usually no very marked difference in the amount of stereome 
present in the upper and lower halves of the section; in Festuca duriuscula and in 
F. rubra, however, the stereome is considerably more abundant in the lower half of the 
leaf-section. 
The leaf is folded in Poa trivialis and P. pratensis, Avena pratensis (Pl. 37. fig. 28), 
and Dactylis glomerata (P1. 38. fig. 31); in all other cases it is rolled. 
li. Grasses of Waste and Sandy Places. 
Grass. Duration. Figure. 
PCE Myro € EE EE eee — 
, var: bromoides — VU, Oe 29g o — 
Phleum pratense, var. nodosum . . . . . . . Perennial. 45 
Mlopeceres.agrestie:: 6: (ii 2088 (leone uta GA — 
Folens mollis 0.22 ie a EET ttt Eeer 42 
TTT 2. 5... dui M ee E ie 43 
Bromus aleriia .. 4... vade | E EE 27 
molts . oe 4222394 ee » a= 
Greef, .- 2. 4 £2  . 6A a EE a 
Poa compressa . . s peat 4 | ee $i wg 
annua s PROS a -— 
Pigida., , V ANUS RO QUI WU » 23 
Sptdiin viridi x Lic od eira ik od y » 20 
Hardewn. murinum 4156-5 lc E E " " 
Agroslis Spieg-tunfi is. nuo hoe S » 22 
Awa Tee e ae ere r » 5 
e EE «pr E E Ee e » m 
a A EE oo s s PUB, — 
EE 7 60. soa VS ARNAL 44 
Tt is interesting to notice in the above table what a large proportion of these grasses 
are annuals, only six out of the nineteen grasses I have collected being perennial, while 
of the twenty-three pasture- and meadow-grasses examined not one is an annual. 
As in the last group, the various forms included here cover a fairly large range of 
habitat. A number of forms included here are common to this group and to Group i., 
others are found on dry banks, others on old walls Ze, On the whole, however, the 
grasses occur in drier situations than do the meadow- and pasture-grasses ; none are 
found in wet places, while in many cases the habitat is distinetly xerophilous. 
When, however, we come to examine the leaf-structure, we find very little difference 
between these and the meadow-grasses, not nearly so much as would correspond with 
the difference in habitat. 
Apart from Aira precor and A. caryophyllea the form of the leaf-section is very 
uniform ; they all show the upper surface of the leaf either perfectly smooth or with 
3D 2 
