18 
THE AUSTRALIAN GARDENER. 
DECEMBER I, 1902. 
> REVIEWS. < 
O- 
KERNER’S “NATURAL HISTORY OF 
PLANTS,” WITH BOTANICAL NOTES, 
BY “ac Sx 
[We shall be pleased to review any books, mag- 
azines, or periodicals dealing with plants sent to 
us for that purpose.—Ep. ]. 
After describing the propagation of 
Ciyptogams, Kerner goes on. to the fruits 
of flowering plants. This branch of 
botany, Carpology, is a most interesting 
one, and may be studied with the help of 
the large carpological collection in the 
Museum of the Botanic Gardens. It must 
be remembered that ‘fruit’ in botany is 
not restricted to edible fruits, but com- 
prises all seed-containing structures. — 
Kerner then takes up Stamens and Pol. 
len. Pollen grains vary very much in 
appearance, and are excellent microscopic 
objects. .See “Edgworth on Pollen” for 
illustrations of these. : 
Hay fever is often attributed to the pol- 
len of the Cape Marigold. If so, I think 
it is not due to the pollen grains them- 
selves, but to their contents. The effect 
on the eyes is more like that of a caustic 
fluid than of a rough grain. 
As might be expected, Kerner devotes 
considerable space to the devices by which 
insects are induced to help in the disper- 
sion of pollen. The allurement is, gene:- 
ally honey secreted by various parts of 
the flower—-the petal, sepal, stamens, 
carpels, and by special nectaries. From 
these it frequently tows into receptacles, 
pouches, and spurs provided in different 
parts of the flower in such positions that 
the insect, in gaining access to them, neces- 
sarily rubs off the pollen, and subsequently 
deposits it on the stigma of another flower. 
The many contrivances for accomplishing 
this are detailed in modern books on 
Botany, from Darwin onwards, and need 
not here be particularised. The other 
branch of the subject, the means by which 
insects useless for pollination purposes 
(such as ants) are kept away from. tho 
honey, is fully worked out in another ci 
Kerner’s books, “Flowers and Their Un- 
bidden Guests.’ Both branches of the 
subject are particularly fascinating, but 
need diagrams or the flowers themselves 
for their elucidation. 
To facilitate the finding of honey manv 
flowers have not only brightly colored 
petals, but special “honey-guides,” or dis- 
tinct markings leading to. the nectaries. 
Dietes Bicolor, a common plant in our 
gardens, is a good example: here the 
petals are yellow, the honey-guide black, 
leading just under the petaloid stigma. In 
Kennedya nigricans I notice thatthe honey- 
guide, in this case red on a nearly black 
ground, only shows itself when the flower 
approaches maturity. On the other hand, 
when maturity is passed the fact is indi- 
cated to passing insects .by the petals 
changing color, 
It is interesting to look round a garden 
to note in what diverse ways flowers ren- 
det themselves conspicuous to the insects 
that may be of service to them. If the 
flewer be pendant, as in the Fuchsia, the 
outside is brightly colored: if turned uap- 
wards, the inside. Sometimes, as in the 
Poinciana, the stamens are long, protrud- 
ing, and conspicuously colored: the Bot- 
tle-brush is a good example of brilliant 
stamen filaments. Bracts, as in Bougain- 
villaea, are sometimes as brightly colored 
as flowers. Look, too, at the colored 
corona in a Passion flower, or the Nav- 
cissus Poeticus. 
But flowers have to consider the special 
likings of particular insects: thus bees pre- 
fer blue and violet; do not care much for 
yellow, and less for scarlet. In this case 
it is suggested that perhaps bees are color- 
blind to red, and do not really see it as 
a distinct color. 
Night-flying moths are most readily at- 
tracted by white ,or pale yellow flowers, 
and these generally supplement their al- 
lurement by special odors. I notice, for 
example, one of the Tobaccos, Nicotiana 
affinis, opens its large trumpet-shaped 
flowers of an evening, and then only is its 
fragrance observable ; whilst it is thus ren- 
dered attractive to useful moths. I note 
that its stem exudes an unpleasantly smell- 
" ing sticky substance, presumably to keep 
away useless ants. 
But not all odors attractive to insects 
are pleasant to man. Flies appear to like 
the Stapelia and the spotted Arum, but 
gardeners call the latter the “Dead-dog 
Lily.” Hawthorn, pear blossoms, and 
Diosma flowers are almost intolerable to 
man from the Trimethylamine they ex- 
hale—an odor comparable to bad fish or 
herring brine. 
TIME OF OPENING AND CLOSING, AND 
Duration or Frowers—Here there is 
much to be noted. Ipomoea opens at 4 
o’clock in the morning, flax between 5 and 
6, Tulips between 9 and 10, and so on un- 
til noon. In the latitude 47 deg. N., 
where Kerner wrote, no plant opens during 
the afternoon: How is it here? At 6 
p-m. the Honeysuckle opens, shortly fol- 
lowed by the Evening Primrose, which 
may be said to burst open, the operation 
taking less than half a minute. Between 
7 and 8 the Marvel of Peru, between 8 and 
9 the Tobacco (already mentioned), be- 
tween 9 and 10 the night-flowering Cereus. 
Some flowers last but a few hours, such as 
the Portulaca; others keep open for days 
or even weeks. Thus a single flower of 
the Cyclamen will last for 10 days: some 
Orchids for one, two, and in the case of 
Odontoglossun Rossii, nearly three 
months. 
ARRANGEMENTS TO PRomoTE CROSSING OF 
FioweErs.—This was well threshed out by 
Darwin, and the conclusion he arrived at 
was that cross-fertilization was a great ad- 
vantage to plants. His conclusion is ac- 
cepted as far as its being a temporary ad- 
vantage, but even his own experiments 
showed that after a time the benefit fell 
Oi 
The arrangements in nature to avoid 
self-pollination are very numerous: the 
anthers and the stigma ripen at different 
times: the anthers open on the side op- 
posite the stigma: the stigma overtops the 
anthers: anthers are in one flower or 
plant: the stigma in another: and so on. 
Tf self-pollination is successfully avoided, 
Kerner shows the numerous contrivances 
to secure fertilization from neighboring or 
distant flowers; but if, after all these 
fail there are equally curious arrangements 
to fall back upon self-fertilization. Ker- 
ner may well call this a “marvel of florai 
construction.” 
“Tn Crocus albiflorus the anthers at first 
rest with their arched backs in contact 
with the stigma, and in this position cross- 
pollination is no doubt effected by in- 
sects. But towards the close of the flower- 
ing period the anthers are twisted round, 
with the result that the pollen touches the 
stigma. 
In the Snowdrop the flower is pendant, 
and the stigma projects beyond the cone 
of anthers; failing’ crossfertilization the 
pollen at a later period falls upon the 
stigma. 
Jn the Aponogeton, grown here as a 
favorite water plant, the anthers are at 
first’ below the stigma, but later on the 
filaments grow and bring the anthers up to 
the stigma. 
In Saxifrage one only out of the five 
filaments thus grows up when needed, the 
others remaining below the stigma. 
Tho Willow-herbs are in the morning 
suited to cross-pollination ; in the evening, 
when the filaments are elongated to ;self- 
pollination. , 
In Azalea the anthers at first stand 
away from the stigma: later on they ap- 
proach and touch it. 
In Cactiform plants the stigma is above 
and out of the way of the anthers at first, 
but after a time the style contracts and 
draws the stigma down on to the anthers. 
When a Campanula flower opens the 
pollen is already shed upon the style, but 
the upper surfaces of the three stigma 
lobes are horizontal and out of the way 
of the pollen below: when the flower is 
older the stigma-lobes roll back, and the 
inner surfaces touch the pollen. 
Passing over numerous other contri- 
vances to effect the same purpose, we come 
to one so simple as to be overlooked. 
At the last stage of the flower the corolla 
becomes detached, and, slipping over the 
style, drags the anthers over the stigma: 
verily a last chance. 
Pollination leads to fertilization. The 
pollen grain lying on the moist stigma 
puts out a tube, which grows downward in- 
side the style, enters the ovary, creeps 
along its walls, and, finding an ovule, en- 
ters by the little spot called the “micro- 
pyle” (“little gate”). This is the usual 
method, but in the sheaoak, birch, hazel, 
and some other trees the pollen tube 
passes through the substance of the ovule, 
and does not make use of the little gate., 
(To be Continued.) 
