An Introduction to Nature-studyStenhouse, E. (Ernest)
History
An Introduction to Nature-study
Stenhouse, E. (Ernest)
Natural history -- Study and teaching; Nature study
Examine the flower. Its leaves cannot be distinguished into calyx
and corolla, but are quite similar to each other in size, shape, and
colour. They are therefore called the perianth. The perianth leaves
are united to form a tube. Tear down the tube to see the six stamens
fixed on it. Are they all on the same level? Examine the pistil and cut
the ovary across to see the ovules in the three joined carpels. Which
is fixed at the higher level, the perianth or the base of the pistil?
2. Other plants of the lily family.—Examine also the white
lily, tulip, star of Bethlehem, and lily of the valley, and notice that
in spite of small differences they are all monocotyledons (how do you
know this?) and all have the perianth fixed below the ovary.
[Pg 120]
3. The snowdrop.—Compare and contrast the snowdrop (Fig. 95).
Make out that it is a monocotyledon, but that its perianth is inserted
above the ovary. This is the great point of difference from the lily
family. Notice also how the stamens are fixed.
Fig. 94.—Wild Hyacinth.
(× ₁₀.)
Fig. 95.—Snowdrops. (× ¼.)
4. Other plants of the snowdrop family.—Examine the daffodil
(Figs. 55 and 96)
and narcissus. Arising from the short perianth tube of the daffodil
is a longer one which is often mistaken for a corolla; it is called
the corona. None of the flowers hitherto described contains anything
corresponding to a corona. The corona in the narcissus is short. As in
the snowdrop, the perianth is fixed above the ovary. Observe how the
stamens are fixed, and notice the dry leaf beneath the flower.
The lily family.—Either the wild hyacinth (Fig. 94)
or the cultivated single hyacinth may be taken as a good representative of
[Pg 121]
this family. The first point which strikes the student on examining the
general “habit” of the plant is the character of the long sheathing
leaves. Their veins do not form an obvious network, such as is
seen in the leaves of dicotyledons, but run lengthwise and roughly
parallel to each other in the manner characteristic of grasses and
other monocotyledons (p. 40). The leaves are narrow, and
are not divided into blade and stalk; they and the flower stalk spring from
an underground bulb (p. 84) which consists chiefly of the
swollen leaf-bases of a previous season. A separate calyx and corolla are not
to be distinguished in the flower; the six leaves being all alike in
size, shape, and colour. These six leaves hence receive a special name,
and are called the perianth. The perianth leaves are united into
a tube, on the inside of which the six stamens are arranged in two
series of three each. In the middle of the flower, and fixed above
the insertion of the perianth, is the pistil, which consists of three
united carpels.
Fig. 96.—Daffodil flower,
cut down the middle. (× ⅔.)
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