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Nature
(Thursday, November 4, 1869)

Bennett, Albert W.
On the fertilisation of winter-flowering plants,   pp. 11-13


Page 11


Nov. 4, I 869]
NA TURE
followed, until the notions which represented Goethe's
superlative are now the commonplaces of science-
and we have a super-superlative of our own.
  When another half-century has passed, curious readers
of the back numbers of NATURE will probably look
on our best, "not without a smile;" and, it may
be, that long after the theories of the philosophers
whose achievements are recorded in these pages, are
obsolete, the vision of the poet will remain as a
truthful and efficient symbol of the wonder and the
mystery of Nature.                  T. H. HUXLEY
  ON THE FERTILISA TION OF WINTER-
             FLOWERING PLANTS
T HAT the stamens are the male organ of the flower,
     forming unitedly what the older writers called the
"andrcecium," is a fact familiar not only to the scientific
man, but to the ordinary observer. The earlier botanists
formed the natural conclusion that the stamens and pistil
in a flower are intended mutually to play the part of male
and female organs to one another. Sprengel was the first
to point out, about the year 1790, that in many plants the
arrangement of the organs is such, that this mutual inter-
change of offices in the same flower is impossible; and
more recently, Hildebrand in Germany, and Darwin in
England, have investigated the very important part played
by insects in the fertilisation of the pistil of one individual
by the stamens of another individual of the same species.
It is now generally admitted by botanists that cross-ferti-
lisation is the rule rather than the exception. The various
contrivances for ensuring it, to which Mr. Darwin has
especially called the attention of botanists, are most beau-
tiful and interesting; and the field thus opened out is one
which, from its extent, importance, and interest, will
amply repay the investigation of future observers. For
this cross-fertilisation to take place, however, some foreign
agency like that of insects is evidently necessary, for con-
v eying the pollen from one flower to another. The question
naturally occurs, How then is fertilisation accomplished in
those plants which flower habitually in the winter, when
the number of insects that can assist in it is at all events
very small ? I venture to offer the following notes as a
sequel to Mr. Darwin's observations, and as illustrating a
point which has not been elucidated by any investigations
that have yet been recorded. I do not here refer to those
flowers of which, in mild seasons, stray half-starved speci-
mens may be found in December or January, and of which
we are favoured with lists every year in the corners of
newspapers, as evidence of " the extraordinary mildness
of the season." I wish to call attention exclusively to
those plants, of which we have a few in this country,
whose normal time of flowering is almost the depth of
winter, like the hazel-nut Corylus avel/ana, the butcher's
broom Ruscus aculeatus, and the gorse Ulex eurofaeus;
and to that more numerous class which flower and fructify
all through the year, almost regardless of season or tem-
perature; among which may be mentioned the white and
red dead-nettles Lamium albumn and furfureum, the
Veronica Buxbaumii, the daisy, dandelion, and groundsel,
the common spurge Eujhorbia fieflus, the shepherd's
purse, and some others.
  During the winter of 1868-69, I had the opportunity of
making some observations on this class of plants ; the
result being that I found that, as a general rule, fertilisa-
tion, or at all events the discharge of the pollen by the
anthers, takes place in the bud before the flower is opened,
thus ensuring se4f-fertilisation under the most favourable
circumstances, with complete protection from the weather,
assisted, no doubt, by that rise of temperature which is
known to take place in certain plants at the time of flower-
ing. The dissection of a flower of Lamium album (Fig.
A) gathered the last week in December, showed the
stamens completely curved down and brought almost into
contact with the bifid stigma, the pollen being at that time
freely discharged from the anthers. A more complete
contrivance for self-fertilisation than is here presented
would be impossible. The same phenomena were ob-
served in Veronica Buvbaumii, where the anthers are
A
                   A. LAMITUM ALBUM.
         x. Section of bud, calyx and corolla rcmoered.
         2. Stamen from bud, enlarged, discharging pollen.
almost in contact with the stigma before the opening of
the flower, which occurs but seldom, V. agrestis and polita,
the larger periwinkle Vinca major, the gorse, dandelion,
groundsel, daisy, shepherd's purse, in which the four
longer stamens appear to discharge their pollen in the
bud, the two shorter ones not till a later period, Lanium
purfiureum, Cardaamine hirsuta, and the chickweed Stcl-
laria media, in which the flowers open only under the
influence of bright sunshine. In nearly all these cases,
abundance of fully-formed, seed-bearing capsules were
observed in the specimens examined, all the observa-
tions being made between the 28th of December and the
20th of January.
  In contrast with these was also examined a number of
wild plants which had been tempted by the mild January
to put forth a few wretched flowers at a very abnormal
season, including the charlock Sinapis arvensis, wild
thyme Thymus serfiyllumn, and fumitory Fumaria offi-
cinalis; in all of which instances was there not only no
pollen discharged before the opening of the flower, but no
seed was observed to be formed. An untimely specimen
of the common garden bean Faba vulgaris, presented
altogether different phenomena from its relative the gorse,
the anthers not discharging their pollen till after the
opening of the flower; and the same was observed in the
case of the Lamium Galeobdolon or yellow archangel (Fig.
B) gathered in April, notwithstanding its consanguinity
to the dead-nettle.
  Another beautiful contrast to this arrangement is
afforded by those plants which, though natives of warmer
climates, continue to flower in our gardens in the depth of
winter. An example of this class is furnished by the
common yellow jasmine, 7asminiutm nudilorumi, from
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