18 
THE AUSTRALIAN GARDENER. 
APRIL I, 1903. 
SCIENTIFIC. 
>COoctS : 
FERTILIZATION OF FLOWERS. 
(By Sicma ) 
This article deals with a subject of vast 
importance in the realm of botany, and one 
which ought to open your eyes to the won- 
ders of vegetable life, wonders which exist 
not only in literature, but everywhere 
around us, at our yery doors, and in the 
most ordinary of gardens. If I am able 
to direct your attention by a few examples 
and illustrations to this most fascinating 
branch of botany, I hope you will use your 
eyes after being opened, and discover for 
yourselves other cases of equal importance 
and interest. This article can only suggest 
to you what to fook for; personal observa- 
tion must do the rest. 
Before, however, proceeding to the sub- 
ject matter proper I must draw your atten- 
tion to certain parts of the flower which 
aro essential to fertilization and the sub- 
soquent perpetuation of the species. : “Be 
fruitful, and multiply on the earth” was 
the command given by the Creator when 
animal life was brought into being. To ‘he 
vegetable world also the command is ap- 
plicable. Individuals have died in vast 
numbers, but the type remains much the 
same throughout all generations. As 
Tennyson puts it when speaking of 
Nature: 
So careful of the type she seems, 
So careless of the individual life. 
In describing the parts of a flower essen- 
tial to fertilization I must necessarily in- 
troduce you to some elementary botany, 
but I hope those among my readers who 
have gone far beyond the A B C of botany 
will be patient. ; 
The stamens and pistil are the portions 
of the flower through whose agency fertili- 
zation takes place. The pistil being asso- 
ciated with the seeding part of the flower, 
yiz., the ovary, has always been considered 
as female and the stamens as’male. In 
one great class of plants these organs are 
plainly visible, and are easily studied. On 
account of their conspicuousness the class 
receives its name, meaning “conspicuous 
marriage.’ Where in plants these essential 
parts are hidden, as in the fern, the class 
name means “hidden marriage.” 
Generally speaking, all the parts of a 
flower are modified leaves, and traces of the 
original leaf form can be readily detected. 
This Nature shows by turning the petals of 
flowers into green leaves (called a freak) ; 
also in double flowers the stamens become 
converted into petals (the Rose). Curiously 
enough, too, parts of a flower are always 
even multiples of one another; thus, 5 
petals, 10-20 stamens, and so on. 
1. The Stamen.—Let us look at, first, the 
stamens. Each consists of a stalk or fila 
ment, and at the extreme end an anther, 
the latter containing a powder (generally 
yellow), which, when ripe, bursts from little 
bags which hold it. Of course, I am only 
_ describing a typical and simple stamen, as 
all sorts of modifications exist, some of 
which make it almost unrecognizable; for 
instance, the filament may be entirely 
wanting, or, as in the pea tribe, 9 of the 
filaments may be joined into a tube, leay- 
ing one free. In passing, I may mention 
that the Tetratheca (four lobes) has been 
so named because there are four lobes in- 
stead of the usual two in the anthers. The 
anther may be fixed firmly, or it may be 
balanced midway and swing about with ihe: 
wind. The pollen referred to above is in 
fine grains of various shapes, and under the 
microscope is a beautiful object. In orchids 
(one of the distinguishing features) the pol- 
len is in large masses, each mass having a 
supporting stalk; but more of this anon. 
Ne, IL 
2. The Pistil—tThe pistil consists of two 
parts, the style or column, generally round 
and with a minute channel down the 
centre; and the stigma (at the top), this 
being of all shapes, but always provided 
with a sticky substance near the apex. 
Immediately underneath the pistil are 
the seed vessels. Fertilization takes place 
when the pollen from the stamens becomes 
attached to the stigma’s sticky surface. 
Fine thread-like microscopic _ processes 
travel down the style and reach the ovaries, 
and as a result seeds are produced. 
In a nutshell, then, the whole process of 
fertilization consists of the transference of 
the pollen from the stamens to the stigma. 
How this transference is brought about in- 
troduces us to the most interesting part of 
the subject. 
Before proceeding further I must remind 
you that there are three great division» 
of flowers relatively to their fertilization. 
First, the male (stamens), and female 
(pistil) may be both present in the same 
flower. 
Second, there may be male flowers on one 
part of the tree and female flowers on an- 
other, i.e., flowers with stamens only, and 
flowers with pistil only, but on the same 
bush ; and ( 
Third, the male flowers may be on one 
bush, and the female on another: In order 
that you may be able to see this for your- 
selves, let me give you examples of the - 
two latter divisions, the first, of course, 
being very common. 
The cucumber, castor oil, mulberry, have 
male flowers separate from the female on 
the same plant. The willow, date, poplar, 
sheoak, anguillaria, carob, have male on 
one plant and female on another. 
A. female willow, it is said, has never 
been known, all the willows of the world 
having been produced by cuttings from one 
original tree in Babylon. 
Date palms are common about Adelaide, 
but none produce mature fruit. In Arabia 
the Arabs collect from the male tree the 
flowers that have the pollen, and, climbing 
the female trees, shake the pollen on to 
the female flowers, thus fertilising them. 
Now there are three well-known methods 
by which the transference of pollen may 
take place, and cause fertilization ; first, by 
seli-fertilization, as is the case when the 
pollen is carried from anthers to pistil in 
the same flower; a most natural and easy 
performance you would say, seeing that the 
two organs are so close to one another in 
the flower; nothing could be more likely. 
Second, by the wind blowing the pollen 
from flower to flower. Third, by insects 
carrying it from flower to flower, i.e., from 
the stamens of one to the stigma of an- 
other. JI will deal with these in order. 
SELF-FERTILIZATION.—The great Darwin 
laid it down as a law deduced from experi- 
ments that “Nature abhors perpetual self- 
fertilization.” He was led to this conclu- 
sion. by the fact that when he crossed one 
flower with the other the resulting plants 
were more vigorous and healthy than those 
produced by self-fertilization. We often 
find analogies between the animal and 
vegetable world, and very striking they are 
somctimes. Just as we know that blood 
marriages tend to exaggerate peculiarities 
even. to insanity, so it would seem that self- 
fertilization. of flowers tended to degeneracy 
in the same way; also it is known that 
a cross may be produced in the animal 
world between different species, but their 
offspring will not breed—for instance, be 
tween the hare and the rabbit—so in tho 
plant world “hybrids” may be produced by 
crossing two different species, but no seeds 
are ever formed by these hybrids. There is 
no denying that self-fertilization does take 
place in plants, and to a very considerable 
extent, but'in many cases it is apparently 
a last resource when other methods fail. 
I shall have occasion, however, to refer to 
this later on. 
Winp Ferrinization.—Wind is an agent 
which becomes of great service in carrying 
pollen, from flower to flower’, often over long 
distances. The pollen in such cases is 
generally very dry and light, and is pro- 
duced in great quantities, because a large 
percentage may be lost in transit and thus 
wasted; for the same reason the stigma 
is very large and feathery. At times 
the pollen covers the ground as if sulphur 
had been lavishly strewn about. The an- 
thers are turned outwards away from the 
stigma to prevent self-fertilization. The 
nettle flings pollen in the air. The fine 
wind-blown pollen of some plants is very 
irritating to the throat, nostrils, and eyes, 
and in some cases causes what is known as 
“hay fever.” 
(To be Continued.) 
