28 BRITISH SPECIES 
Poa pratensis, var. subcerulea, isa dwarf glaucous purplish form, 
found on wall-tops, dry heaths and mountains. 
Deschampsia cespitosa, var. brevifolia; leaves short, panicle 
much smaller than in the typical plant; dry uplands, mountains. 
The grasses forming our third group are semi-aquatic, growing 
in ditches, ponds and marshy places, and by the margins of rivers 
and streams. 
Alopecurus geniculatus, the Floating Foxtail, is a very common 
grass all over Britain, in ditches, ponds and marshy places. Root- 
stock with decumbent and geniculate branches, rooting below, 
; often floating. Leaves short with 
rough ribs, dull green. Culms about 
a foot high, sharply bent at the lower 
nodes. Panicle spikelike, cylindric 
and dense, much narrower than that 
of A. pratensis, and purplish-green. 
Spikelets $5 inch long, 1-flowered ; 
empty glumes awnless, united at the 
base and ciliated on the keel ; flower- 
ing glume with a sub-basal awn 
nearly twice its length; no palea. 
Perennial, flowering early June to 
autumn. <A. fronus is a prostrate 
form. 
Glyceria fluitans, the Floating Sweet- 
grass (fig. 22), almost invariably ac- 
companies the species last described, 
but is not confined to stagnant water, 
as it fringes the rivulets, and often 
floats in the current. Rootstock with- 
out subterranean stolons, but produc- 
ing stout procumbent or floating 
branches which root below. Leaves 
Fic. 22.—Glyceria fluitans: a long, broadly linear, conduplicate at 
iat and lover potion of anise first, then flat, with faint ribs, flaccid, 
wise, showing scarious tips of Speckled in transmitted light ; ligule 
glumes. prominent. Culms about 2 ft. Pani- 
cle long and slightly branched, the 
branches adpressed to the rachis, and some of them bearing only 
one spikelet. Spikelets about an inch long, cylindric at first, then 
linear and compressed, pale green, 12- to 15-flowered; glumes 
rounded on the back and awnless, the flowering ones with 7 nerves 
which vanish below the colourless tip. Perennial, flowering early 
June to autumn. Sub-species G. A/cata has leaf-sheaths distinctly 
furrowed, the panicle more branched and spreading in fruit, lowest 
branches about five; flowering glumes twice as long as broad, 
3-toothed. Var. G. pedicellata has also furrowed sheaths, lowest 
panicle branches in threes. Var. G. declénata is a dwarf state with 
smooth sheaths, spikelets few-flowered and palea longer than the 
SSS 
eID 
