102 
AMERICAN AGRICULTURIST. 
[March, 
hare become well known ; whether they were re¬ 
garded as of difficult cultivation, or the fashion had 
not set in then- favor, we do not know, but while 
they were formerly only to be found in large col¬ 
lections, they have of late become exceedingly 
popular plants. There is scarcely any genus that 
affords plants suited to such a variety of uses. 
There is one set cultivated for the beauty of its 
foliage only ; another for its brilliant winter-bloom¬ 
ing flowers; another gives both ornamental foliage 
and pleasing flowers, and lastly, another group, all 
the foregoing being for the greenhouse, which 
affords most charming border or bedding plants. 
They present, also, a great variety in habit; some 
have very short stems and enormous foliage ; others 
grow two feet or more high, with small leaves; 
some have a prostrate or half climbing habit, that 
fits them for use as basket plants, and then another 
with large tubers, which can be dried off and stored 
away, like a gladiolus bulb. Being natives of the 
warmer parts of America, some few being from the 
East Indies, we should not look among them for 
hardy plants, yet some of the tuberous-rooted kinds 
are hardy in England, and no doubt would be so in 
the warmer portions of our own country. Those 
who have greenhouses, fiud Begonias most useful 
plants ; they possess two excellent qualities : they 
are propagated with ease, and they may be kept 
small or large, as one may wish ; put a plant in a 
three-inch pot, and it will do its very best, and it 
can do no more in a six or eight-inch pot, except to 
be larger. The ease with which they are managed, 
and the great variety in their foliage and flowers, 
make them most valuable for greenhouse decora¬ 
tion. It is not necessary to enumerate species and 
varieties, as the catalogues do that. We give an 
engraving of a single leaf and flower stem of 
one which has afforded us much satisfaction for 
several winters, it being of the group that are orna¬ 
mental in both foliage and flower. It is Begonia 
hydrocotylifolia —that is, with leaves like Hydrocotyle, 
and if one is a stickler for English names for plants, 
he can say the “Water-Pennywort-leaved Begonia.” 
Its rounded, fleshy leaves, are of a rich dark-green, 
are strongly veined above, and reddish beneath, 
and it would be desirable for these alone, but it 
throws up panicles of pinkish, sometimes almost 
white flowers, which are useful for cutting, and it 
keeps on doing so, as if it never would stop. 
Begonias for Window-Culture. 
Among the species and varieties cultivated by 
florists, to furnish cut-flowers in winter, are the 
B. fuchsioides, often called “Coral-drop,” with 
drooping, fuchsia-like, scarlet flowers, and its white 
variety, differing only in color; B. nitida, B. incar- 
nata superbd, bright pink ; B. WeHoniensis, with 
waxy pink flowers, and others. Most of these may 
be grown in a sunny window of a warm room, if 
not over watered, and when well managed make 
charming window plants. But in size and bril¬ 
liancy, as well as in variety of coloring, the recent 
Hybrid Tuberoxis Begonias 
excel all others. These most charming novelties 
may be grown in pots for summer decoration of 
the greenhouse, or they may be turned out into the 
open border, either as single specimens, or massed 
as bedding plants. Some have flowers two to three 
inches in diameter, and are white, pink, orange, 
yellow and the most intense scarlet. New varieties 
are offered every year, and though still rather high 
in price (from 50c. to $1), are well worth all they 
cost, as they may be kept from year to year, and 
easily multiplied. Octopetala, Bolivensis, Sedeni, 
Sutherlandi, Vietchi, Froebeli, and Ne Has Ultra, are 
a few among many of these charming plants. The 
seeds are offered for sale, but our experience with 
these has not been encouraging. Several years 
ago, when these Begonias were first offered, Messrs. 
B. K. Bliss & Sons sent us a few bulbs ; these gave 
so much satisfaction that, seeing the seeds offered 
abroad, we ordered some from one of the leading 
European seed-houses, who made a wonderful 
flourish about them in iheir catalogue ; we raised 
20 or more plants, and they were no doubt tuberous- 
begonias, for they seemed to run all to tuber; after 
keeping the plants in the greenhouse all through 
summer and winter, they were put out to flower. 
Every one produced a miserable little white flower, 
less than half an inch across—but we had a lovely 
lot of tubers. If any have fared better from seeds, 
we should like to know it, and who raised the seeds. 
How Flowers are Fertilized. 
BT PROF. ASA GRAY. 
ARTICLE XI.—THE GOOD OF CROSS-FERTILIZATION. 
We argue that cross-fertilization must be a good 
thiug because there is so much of it, because it is 
provided for in so many cases, and in such various 
ways. And, with our present ideas of how things 
go on in nature, we do not allow that this argument 
is much weakened by the fact that many flowers 
freely self-fertilize, and this may habitually occur 
in the very flowers which are evidently adapted for 
crossing. Cross-fertilization depends on outside 
agencies, and may fail, although it be the best 
thing. Self-fertilization is independent and surer, 
usually secures the immediate purpose well, even 
if not so good in the long run. To make an -agri¬ 
cultural comparison, by self-fertilization we are 
most sure of a crop, by cross-fertilization we are 
more likely to have a long succession of good crops. 
The best compromise, on the whole, is made in 
flowers which cross-fertilize when duly served by 
insects or winds, and self-fertilize when they are 
not. That is a common case, and the flower we are 
going to consider is a good instance of it. 
The common Morning-Glory of our door-yards, 
(Ipomcea purpurea), opens each flower for only one 
day. It opens over night, and on a bright day it 
closes and fades before the sun is high ; on a cloudy 
day it lingers longer. Bees and other flying insects 
freely visit these blossoms; and the flower is adapt¬ 
ed for crossing, the stigma projecting beyond the 
anthers; but the crossing must be done in the 
course of a few hours, or not at all. Here is a great 
risk. “ It might have been thought that it could 
not be fertilized without the aid of humble-bees, 
which often visit the flowers; but as the flowers 
grow older the stamens increase in length, and their 
anthers brush against the stigma, which thus re¬ 
ceives some pollen.” This is from Mr. Darwin’s 
new book, from which we made quotations in our 
last article. There can be only six seeds to a flower, 
and Mr. Darwin found that self-fertilized flowers 
were nearly as prolific as the cross-fertilized. 
Now in case3 like this, one may say that cross¬ 
fertilization is beneficial, and in the long run neces¬ 
sary ; but how are you going to prove it ? The 
theory is plausible ; but facts are wanted for con¬ 
vincing. Mr. Darwin is not a man to go upon 
theory when facts are to be had. He carried on a 
series of experiments upon this very plant for a 
dozen years, and the details and discussion of the 
conclusions fill two chapters of his new book. 
He raised a stock of seedlings, all from one plant, 
and when they blossomed, he close-fertilized one 
set, and cross-fertilized another. The seeds of the 
two sets were saved separately, and were allowed 
to germinate on damp sand. Whenever one seed 
of each set germinated at the same time, he took 
the pair which thus had an even start, planted the 
two on opposite sides of the same small pot, gave 
them equal exposure to light, and equal watering, 
stuck in a similar rod for each to climb on; and as 
soon as one of the pair reached the top of the rod, 
both were measured. Parallel experiments were 
made with a number of such pairs in the same pot, 
the close-fertilized on one side, the cross-fertilized 
on the other, and the maximum growths measured ; 
but the single pairs were mainly relied on. The 
upshot was, that all the crossed plants attained a 
greater height than their antagonists, and that the 
average height of the six crossed plants was 86 
inches, while that of the six self-fertilized was 
65 86 / 1 oo inches. That is the crossed were to the self- 
fertilizcd, in vigor of growth, as 100 to 76. 
The course of experiments was continued for ten 
generations. Flowers of the crossed plants of this 
first generation, were crossed by pollen of other 
plants of the same generation ; and flowers of these 
had an advantage, and the diminution of fertility 
in the self-fertilized generations, showed itself in 
the lesser size of the anthers, smaller quantity of 
pollen, and at length in disposition to monstrosity. 
Trial was made of cross-breeding between differ¬ 
ent flowers of the same plant. But this appeared 
to give no advantage over self-fertilization. Trial 
was made of wider cross-breeding than that of the 
ten generations intercrossed between near brethren. 
A Morning-Glory was raised from seed which grew 
in a distant town, and when its pollen was used for 
the cross, the plants resulting from the union were 
extraordinarily vigorous. When crossed with some 
of the ninth generation of the continuously cross¬ 
bred, the resulting seedlings were “as superior in 
hight, and almost as superior in fertility to the again 
inter-crossed plants, as these were to seedlings 
from self-fertilized plants of the corresponding 
generation. 
This generally held true in other species of plants. 
It shows in a striking way that cross-fertilization is 
beneficial, while it has also been shown that the 
mere crossing of different flowers does little, if any, 
good. The reason why cross-fertilization is benefi¬ 
cial now begins to appear. We will present Mr. 
Darwin’s view of it in the next article. 
A Useful Method of Propagating Plants. 
BY PETER HENDERSON. 
Something Important to Florists—Useful to 
Amateurs-An Easy and Sure Method. 
A good many years ago, we published a method of 
propagating Geraniums, that we believe originated 
with us, and which we called, for want of a better 
term, “ Layering in the Air.” It consisted in tongu- 
ing the shoot to be used as a cutting half through 
with a knife, as in the ordinary layering; the shoot 
so treated formed granulations, or “ callus,” on 
the cut surface, and was in a condition to form 
roots immediately on being detached and put into 
the earth.—Like many other useful practices, this 
was abandoned or forgotten by us, until last fall, 
when we saw that, owing to the unusual dry sum¬ 
mer, our stock plants of many of our finest orna¬ 
mental-leaved Geraniums, and other plants of like 
character, was so apparently lacking in vigor, that 
to detach cuttings in the ordinary way of propaga¬ 
tion, would probably not only result in the loss of 
the cuttings, but be of great injury to the “ stock 
plants” themselves, by so denuding them of leafy 
shoots in their then weak condition. Here we again 
bethought ourselves of our long forgotten plan of 
“ Layering in tUe Air,” 
but this time we improved upon the former way of 
doing it. Instead of tonguing the shoot to be used 
for a cutting, as before, it was merely snapped short 
off, at a point where the condition of the shoot or 
slip would make it hang on to the plant, by the 
merest shred of bark, as shown in the engraving on 
page 100. Slight as this strip of bark appears to 
be, it is sufficient to sustain the cutting, without 
any material injury from wilting, until it forms the 
“ callus,” or granulated condition, which usually 
precedes the formation of roots. The cutting, or 
slip, may be detached in from 8 to 12 days, after it 
has been broken in the manner described ; and then 
potted in 2 or 3 inch pots. If watered and shaded 
rather less than required by ordinary cuttings, it 
will form roots in 8 or 12 days more, and not one in 
a hundred will fail, even of plants of the Tricolor 
Geraniums, which we all know are difficult to root 
under the ordinary modes of propagation, particu¬ 
larly in hot weather. We last fall propagated in 
this way nearly 10,000 plants of the Tricolor class, 
with a loss of one per cent; had we adopted the 
ordinary method, even with the plants in good con¬ 
dition,—our experience has been that a loss of at 
least 50 per cent might have been expected. 
Useful for a Variety of Plants. 
This plan is applicable to many other plants as 
well as Geraniums ; we are now using it with ex¬ 
cellent success on the new double Poinsetta. The 
following plants may be also propagated with great 
certainty by this method, using the young unripen¬ 
ed shoots: Abutilon, Begonias, Carnations, Helio- 
