CLASSIFICATION.
The family Gramineae is usually divided into two series taking into
consideration the presence or absence of a joint in the pedicel or
rachis, the number of flowers in the spikelet and the position of the
fertile flower. All the species in which there is a joint just below the
spikelet, in the pedicel, in the rachis, or at the base of a cluster of
spikelets come under one series =Panicaceae=. The spikelets of the
grasses coming under this series, when mature, fall away singly by
themselves, or with their pedicels, or in groups with portions of the
rachis. The spikelets are all similar and consist of usually four
glumes. Each spikelet contains a single perfect flower and sometimes in
addition a staminate flower just below the perfect flower. In this
series the tendency for imperfection is always confined to the lower
flowers, the terminal flower alone being perfect. For inclusion under
this series the grass plant should have both the characters,
articulation and position of the flower as mentioned above.
The second series =Poaceae= includes those grasses in which the spikelets
are one to many-flowered and continuous with their pedicels. But the
rachilla of the spikelet may be jointed just above the empty glumes or
between the flowering glumes. The complete flower is the lowest and the
tendency for imperfection is in the upper flowers.
Of the two series the Panicaceae appears to be more highly developed than
the Poaceae.
KEY TO TRIBES.
Series I.--Panicaceae.
A. Rachis of inflorescence not jointed.
Spikelets 2-flowered; upper flower
bisexual and lower male or neuter;
the first glume the smallest I. Paniceae.
Spikelets 1-flowered;
Spikelets articulate on their
pedicels and falling away from
them; flowers bisexual and
usually with six stamens II. Oryzeae.
Spikelets falling away with their
pedicels; flowers bisexual or
rarely imperfect III. Zoysieae.
B. Rachis of inflorescence usually
jointed.
Spikelets usually binate (3-nate at
the top), pairs of spikelets alike
or dissimilar; empty glumes
larger and the flowering glumes
smaller, hyaline, the fourth glume
awned or reduced to an awn IV. Andropogoneae.
Series II.--Poaceae.
A. Rachilla produced or not beyond the
flowering glume.
Spikelets 1-flowered, with three
glumes; first and second empty,
third flowering and awned;
rachilla jointed V. Agrostideae.
Spikelets 1- or more-flowered,
biseriate and secund on an
inarticulate spike or on the
spiciform branches of a slender
panicle; flowers all or the
lower only bisexual VI. Chlorideae.
B. Rachilla produced beyond the uppermost
flowering glume and articulate.
Spikelets 2- or more-flowered,
pedicelled, rarely sessile, in
effuse, contracted or rarely
spiciform panicles VII. Festucaceae.
Spikelets 1- or more-flowered,
sessile, 1- to 2- or more-seriate on
the rachis of a simple spike, or
partially sunk in cavities of the
same. Glumes awned or not,
first and second glumes are
opposite or subcollateral,
persistent or separately deciduous;
first glume minute or absent VIII. Hordeae.