Grasses : $b A handbook for use in the field and laboratoryWard, H. Marshall (Harry Marshall)
Science
Grasses : $b A handbook for use in the field and laboratory
Ward, H. Marshall (Harry Marshall)
Grasses
_Alopecurus pratensis._ Leaf thin and somewhat like _Phleum_, but the
ridges somewhat higher and more rounded, and only the principal bundles
girdered below. Stomata on both faces.
_Festuca elatior_, _Bromus giganteus_ and most species of _Agrostis_
come near _Lolium_. See Figs. 17, 22.
CHAPTER VI.
GRASSES IN FLOWER.
When the flowering shoot of a grass pushes up into the light and air
from the enveloping leaves, it forms a more or less branched collection
of flowers known as the _Inflorescence_, and in all our grasses this
inflorescence consists of a principal stalk, _haulm_ or _culm_, on
which shorter stalks--branched or not--are arranged. The mode of
branching is usually such that the youngest branches are nearest the
top, and the oldest nearest the bottom. It is evident at once, on
comparing the Moor Mat-grass (_Nardus_), Vernal-grass (_Anthoxanthum_),
Cock’s-foot (_Dactylis_), Meadow-grass (_Poa_) that considerable
differences exist as to the extent of this primary branching of the
inflorescence.
In _Nardus_ (Fig. 2) we find a number of long cylindrical-tapering
bud-like structures each seated on one side of the principal stem, and
one over the other: in the Vernal-grass and Cock’s-foot we find tufts
of such bud-like structures closely crowded round the upper end of the
principal stalk, the whole forming an elongated tuft of tufts: in the
_Poa_ we find a number of radiating, slender, long branches springing
from the principal stalk, and each of these ramifies again, and yet
again, until each of the ultimate hair-like branches bears one of the
bud-like structures. See also _Catabrosa_ (Fig. 4).
[Illustration: Fig. 29. A spikelet of _Festuca elatior_, var.
_pratensis_, from which the glumes and one palea (the outer) have been
removed to show the flower in situ (× 12). The two lodicules are in
front: the inner palea behind. Strasburger.]
The first thing for the student to apprehend is the nature of the
bud-like structures referred to.
Each of these is in itself a small tuft or bud of leaflike organs or
scales arranged on a short twig (_Rachis_, _Rachilla_), as it were, and
is called a _Spikelet_, and the true flowers of the grass are contained
in the angles between the scales--the scales being popularly known as
“_chaff_”: technically as _Glumes_ and _Paleæ_.
In order to understand the structure of a spikelet the student
should carefully dissect a large one, such as that of an Oat (Fig.
1). Proceeding from outside, he will find two large scales, like two
boats, fixed below to the stalk (_rachis_) one just below the other,
and shutting together as if hinged. These are called the _glumes_--the
inner and outer glume respectively--and they enclose the rest of the
spikelet.
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