198 KEY TO SUB-CLASSES, ORDERS AND GENERA. 
CXX VI—GRAMIN ACE Ai—cont. 
(1) Rachilla not continued beyond the upper floret ; spikelets 2-flowered, 
minute; glumes membranous, rachilla and keel of flowering glumes ciliate ; 
panicle thyrsiform ; leaves as long as, or longer than, the stem, narrow, coriaceous, 
conyolute ; stems rigid, as thick as a crow-quill, base woody :— .... mxxxvi—Zenkeria, 
(2) Rachilla continued beyond the upper floret, or if not continued 
(Phragmtes), then elongated between the flowering glumes and penicillately 
hairy ; spikelets not awned, or if awned, then the awn nut twisted :-— 
(A) Spikelets conspicuous, not in globose clusters ; flowering glumes 
1—3-nerved :— 
(a) Spikelets penicillate with long silky hairs on the flowering 
glumes or callus, or both, and paniculate :— 
(A) Flowers hermaphrodite ; lowest fluwering glume sometimes 
male or neuter :— 
(*) Rachilla glabrous; flowering glumes dorsally hairy beyond 
the middle ; leaves flat ; tall stout perennial grasses :-— 
mxxxvii—Arundo. 
(**) Rachilla hirsute ; flowering glumes glabrous; leaves long; 
tall perennial grasses :— zoe ..» mxxxix—Phragmites. 
(6) Flowers dicecinus; spikelets 2-flowered ; panicles large, 
silvery white, feather-like ; leaves very long, linear, 
glaucous green, with rough edges; tall perennial grasses :— 
mxxxvill—UGynerium, 
(b) Spikelets not penicillate with long silky hairs ; many-flowered :— 
(a) Outer glumes longer than the lowest flowering glumes : grain 
broad concave; leaves very long, flat; tall, stout, glabrous, 
perennial grass of marshes:— _ ... ... mxxxix—Myriostachya,. 
(8) Outer glumes shorter than the lowest flowering glume; grain 
ellipsoid, compressed, grooved ; leaves narrow, rigid, con- 
volute ; tall, stout, perennial, glabrous grass, with branching, 
creeping, sheathed rootstock, of the sea-coust :— 
mxli—Halopyrum. , 
(ii) Leaf blades transversely veined (tessellately nerved), flat and arvicu- 
lated to the sheath by the petiole ; spikelets 1—4-flow=red, secund, biseriate on 
the rachis of a simple spike ; tall erect perennial grass :— -. tmxlii—Streptogyna. 
(iii) Leaf blades transversely veined (tessellately nerved), flat and articu- 
lated to the sheath by the petiole; syikelets 1-to many-flowered, in spikes, 
heads, whorls, racemes, or panicles, simple or panicled, but not in secund bise- 
riate spikes :—(BaMBUSE®) :— 
[Anatomical features.—Perennial grasses, as a rule of extremely gregarious habit. 
A woody rootstock or rhizome, consisting, in the case of tufted spacies, of short twisted 
entangled branches, producing a large number of more or less closely packed woody 
stems (culms), or, in the case of single-stemmed species, with long creeping branches 
producing a number of culins from 1 to 3 feet apart. The culms are jointed, hollow 
between joints, rarely climbing, usually erect, the outer culms of the clump often 
overhanging, in Some species the culms almost lyingonthe ground. The young shoots, 
which come up inthe rainy season, either in the midst of dense clumps or, in the single- 
stemmed species, separately from the ground, have the full diameter of the culm, but 
are quite soft. They are enclosed in large, generally coriaceous, sheaths, often hairy 
outside, which arise from the joints or nodes, and as arule terminate in a more or 
less imperfect blade. These sheaths, like those which bear the ordinary green leaves 
of the bambucs, are strictly alternate, there is an angle or interval of 180° beuween the 
axillary buds of two successive sheaths. ‘he general appearance, length, texture, and 
shape of these sheaths and their blade afford good characters for distinguishing the 
different species. The leaves are distichous, and consist of a tubular sheath, split to 
the base, and a linear-oblong or lanceolate blade with a midrib and numerous longi- 
tudinal veins (fibrovascalar bundles), usually of two classes, stout or coarse and thin, 
generally 5-9 thin between two stout nerves. The blade is joined to the sheath by a 
short petiole. Half way between two longitudinal nerves, and parallel to them, is a 
transparent band, due to several lines of large celJs, belonging to the upper epidermis, 
which are frequently (but not iu all.cases) filled with bright colourless masses of silica 
(silicon dioxide). All bamboos have transverse veins, consisting of wood fibres, which 
run across from one longitudinal nerve to the next, straight, oblique, or with a bend in 
middle, In many species thes® transverse veins are conspicuous, particularly on dry 
