OF THE LEAVES OF BRITISH GRASSES. 335 
especially in the arrangement of the chlorophyll-tissue, the small amount of stereome present, &c. 
Poa loliacea is rather more strongly xerophilous in its leaf.structure than P. rigida, and in both the 
distribution of the motor cells is significant.] 
TT Chlorophyll-tissue normal in type. Stomata more numerous above. 
LOLIUM TEMULENTUM (Pl. 37. fig. 24). Royal Botanic Garden, Edinburgh. July 1901. 
Dome-shaped ribs on upperside; midrib not specially marked. Larger bundles half- 
girdered below and with bands of stereome above, others with bands above and below ; 
smaller ones with bands above only. Outer sheath to bundles well marked, inner less so. 
Chlorophyll-tissue interrupted at most of the larger bundles. 
With a similar habitat, the leaf-structure of the two species of Lolium is also very 
much the same. In both cases it is fairly typical for meadow-grasses. 
ALOPECURUS ALPINUS (Pl. 37. fig. 25). Royal Botanic Garden, Edinburgh. April 1901. 
Stomata very abundant, especially on upperside. Vascular bundles few. Stereome 
in bands at summits of ridges, below bundles, and below groups of motor cells. 
Chlorophyll-tissue very loose. 
tf Motor cells not conspicuous. 
§ No hairs or asperities. Stomata more numerous above. 
AGROSTIS VULGARIS, var. PUMILA (Pl. 36. fig. 10). (See p. 329, above.) 
$8 A few short hairs or asperities. 
|| Rather sparse, short, stiff hairs both sides. 
ALOPECURUS AGRESTIS. Fulbourn, Cambs. July 1900. 
Upperside with ribs rounded and uniform. Ribs slightly marked below. Stomata 
about equal on the two sides. Vascular bundles with double sheath, though the outer is 
not always clear. Only oneor two bundles girdered, others with bands of stereome above 
and below, or above or below only. Bands also under lower epidermis between the ribs. 
II Asperities on upper surface only. 
LOLIUM PERENNE. Burntisland, Fife. May 1901. 
Well-marked ribs on upperside, flat below. Stomata more abundant above. None of 
the bundles girdered ; bands of stereome above and below all the bundles. 
Quy, Cambs. August 1901. (Inflorescence branched.) 
' Differs only in that a few of the ribs are slightly marked below. 
ALOPECURUS GENICULATUS (Pl. 37. fig. 21). Melrose. June 1901. 
Lower side smooth. Epidermal cells somewhat papillose, especially above. Stomata 
very abundant on both sides. Vascular bundles of two orders ; those of first order have 
both sheaths well marked, but in those of second order the inner sheath is not 
conspieuous. Small bands of stereome above and below all bundles, and on lower side 
between them, opposite the motor cells. 
