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
A curious phenomenon is observed in some grasses growing in high
latitudes, or mountainous regions, or in moist situations. The
flowers, or even entire spikelets, grow out into minute leafy buds,
with rudimentary roots at the base, and fall off like the bulbils
of other monocotyledons, taking root directly in the damp soil.
The phenomenon must be looked upon as a case of apogamy, since the
development of sexual organs is entirely passed over; the parts which
would normally have become ovary and stamens being transformed into
leaves. In some species or varieties--e.g. _Poa alpina_, _Festuca
ovina_--this viviparous condition may coexist with normal flowers
and spikelets; in others--e.g. _Poa laxa_, var. _stricta_--only the
viviparous state occurs.
In the following arrangement the student should note that the terms
“Seed” and “Fruit” are used in the ordinary sense of the farmer and
seedsman: by the former is meant the “seed” as it comes in samples
into the market, when the true fruit or grain (_Caryopsis_) is almost
invariably invested by adherent “chaff”--i.e. paleæ or glumes or
both. When the word Caryopsis is employed, I mean it strictly in the
botanical sense explained above. In _Hordeum_, for example, we never
see the true fruit, the grain consisting of the caryopsis with paleæ
so closely adherent to it, that we are apt to take them as part of
the grain itself. The true seed, in the strict botanical sense, is
never seen as a naturally separate organ in our native grasses; and,
as already explained, only very few exotic grasses ever shed it--e.g.
_Sporobolus_.
CHAPTER IX.
CLASSIFICATION OF GRASSES BY THE “SEEDS” (GRAINS).
+I. “Seed” rounded (Millet-seed[12] type). Caryopsis ovoid or
sub-globose, devoid of distinct groove, and distending the awnless
paleæ, or falling out free.+
+A. Glumes cuspidate, “fruit” yellowish.+
_Phleum pratense._
The student should familiarise himself with the “seed” of _Phleum
pratense_, as a type, and an important grass easily obtained pure, but
sometimes with minute round seeds of weeds intermixed.
_Phleum pratense_, L. (Fig. 45).
Palea 2·3 mm. long, five-ribbed, with a short point, delicate but hard,
smooth, with a silvery lustre. Inner pale two-nerved. Closely investing
the yellow-brown caryopsis, which easily falls out and is ovoid-acute,
about 2 mm. long by 1 broad, and finely punctate.
The much rarer _P. arenarium_ and the very rare _P. Bœhmeri_ and
_P. asperum_ also come here.
Public-domain text, read in full here on John Shaqi.
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