The Vegetative Anatomy of Molinia cserulea. 65 
IV. Leaf. 
Unlike its associates Aira flexuosa and Nardus stricta, whose 
leaves are setaceous through permanent inrolling, Molinia has a 
ribhon leaf. When wilting it rolls up considerably, and in dry seasons 
makes use of this power to reduce evaporation : but normally its 
leaf is flat. The sheath is split to the base ; the ligule is represented 
by a tuft of hairs, a useful character for identification ; the linear 
lanceolate blade is long, thin, smooth, tapering slightly to the ligule 
and running off above into a long fine tip; though thin, the blades 
are exceptionally rigid : Ward (4) mentions that they are used 
locally for brooms; there is a slight covering of hairs on the upper 
surface, especially towards the ligule; the margin has a series of 
very fine teeth, which are outgrowths of the epidermal cells with 
walls containing a siliceous deposit. 
Of this leaf, some account of which has been given by Lewton 
Brain (3), the under surface in transverse section is fairly even, 
while the upper is thrown into a series of low ridges. These ridges, 
of which there are eleven to fifteen on either side of the midrib, 
indicate the position of most of the vascular bundles, while the 
hollows are occupied by groups of motor cells. The vascular 
bundles are large and are made still more prominent by being 
girdered with stereome. According to the disposition of this 
stereome, which varies with the size of the bundles, the latter 
may be distinguished as of four types: midrib, main lateral bundles, 
secondary lateral bundles, and supporting bundles. The midrib is 
a large bundle with stereome passing to both surfaces and spread 
out on the under side into a broad sub-epidermal band, giving an 
inverted T section. The main lateral bundles occupy about every 
third ridge from the midrib to the margins; their outline is practi¬ 
cally circular and they fill up three-quarters of the thickness of the 
leaf under the ridge (see Fig. 7); broad flanges of strengthening 
tissue pass from these bundles to both epidermises, but do not 
spread out as in the case of the midrib. The secondary lateral 
bundles occupy the remaining ridges ; they have only about a third 
of the area in cross section of the main ones, and are of ovoid 
outline with the broad end of the egg towards the under surface. 
these also are girdered above and below, but the mechanical tissue 
is but a narrow strip. The supporting bundles are a small pair 
on the flanks of and parallel to the midrib ; they have a band of 
stereome below them passing to the epidermis but none above ; 
