An Introduction to Nature-studyStenhouse, E. (Ernest)
History
An Introduction to Nature-study
Stenhouse, E. (Ernest)
Natural history -- Study and teaching; Nature study
A horse chestnut twig.—A winter twig of horse chestnut (Fig. 37)
[Pg 63]
is very similar in its general features to what we have seen in
the sycamore. The buds are in pairs at right angles to each other,
and below each bud is a large corky leaf scar (l.s. Fig. 38),
with the positions of the former food-pipes marked by black dots (v.b.).
These buds, however, are larger than those of the sycamore, and each is
covered with a shining layer of resin, to keep out insects and the rain.
We may slip the end of a penknife under the bud scales and remove them
one by one. The first few are thin and papery, and soaked in resin.
Those next inside are woody and much thicker. Next comes a layer of
papery scales, inside that a coat of cottony down, then another soft
papery layer, and lastly a thick pad of down. When we carefully scrape
away this down, we find—warm and cosy in its midst—a tuft of little
objects with a most quaint resemblance to hands clad in woollen gloves.
We remove one of these, and on scraping it gently with a knife we see
that the “hand” has seven fingers; and it presently becomes clear that
each finger is a tiny green leaflet folded on itself, and that the hand
is a young leaf. If we take off these gloved leaves in turn one by one,
we find as we proceed that they become smaller, until they are almost
too small to be distinguished in their fluffy nest. And when all the
down and the baby leaves are scraped away, the tender growing point
of the twig is left alone at the summit of a little cone, with steps
showing where the leaves were.
Had the twig been left undisturbed on the tree, the bud would have awakened in spring and begun to grow
(Fig. 39).[7]
The scales and the down would have been shed, leaving only the rings of
scars as a memento of the winter sleep; the growing point would have
pushed on and on, lengthening perhaps a foot or more in three weeks;
[Pg 64]
the leaves would have opened their bright green fingers to the spring
air, and begun their work (Fig. 40), only to
cease when in the autumn they too dropped off, and the new buds
tucked themselves up in their beds to go to sleep. The leaves of the
horse chestnut fall off, as do those of the sycamore, owing to a
“separation-layer” arising at the base of the leaf stalk (Fig. 41),
and in this case each leaflet also becomes separately detached in the same way.
Fig. 39.—Later stage of the Horse Chestnut
twig of Fig. 37. (× ¹ ₉.)
Fig. 40.—The later development of the terminal
bud of the twig of Figs. 37
and 39. (× ⅕.)
Other forms of buds.—Surrounding the young silky-fringed leaves
of the beech bud are several crimson membranous scales which are
really the stipules (p. 43) of undeveloped leaves. The thin, soft parts
of the leaf blade are sharply pleated (Fig. 42)
between the side veins which spring from the midrib.
[Pg 65]
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