January, 1920 
t3h<t Slower (Brower 
13 
Self-Pruning in Plants. 
BY WILLARD N. CI.UTE 
(in New York Sun ) 
cormels is to not give them any special 
treatment, but we see that they are 
stored in moist sand for at least a 
month before planting. Indeed, if 
some of the cormlets sprout before 
planting it does not seem to be any 
disadvantage. It is common practice 
to store cormels after separating from 
the corms in sand which is a little 
moist, but if the cormels are green and 
not cured much we believe that placing 
them in dry sand for a short time to 
prevent molding is better practice than 
to place them in damp sand. After a 
few weeks they may be transferred to 
sand which is slightly moist. 
Various plans are resorted to for 
treatment of cormels before planting, 
some growers soaking in cold water 
for two or three days and still others 
soaking them in warm water for twelve 
hours or more before planting. Cor- 
mels, if rare and valuable, may be 
pealed before planting. 
Madison Cooper. 
Vitality of Gladiolus 
Corms from Bulblets. 
To the Editor 
I am told that bulblets from bulblet grown 
stock produces weak corms and that only 
bulblets from large sizes should be used to 
increase stocks. The same party tells me 
that they do not use the bulblets from small 
stock to increase stock in Holland. Is this 
a fact ? J. M. 
Answer : — We have never heard, nor 
have we ever noticed in our experience 
that bulblets from bulblet grown stock 
produce bulbs essentially different in 
constitution than bulblets from the 
larger sizes. In fact we have always 
mixed the bulblets from the different 
size stock without thinking that there 
was any difference and so far as we 
know there is no difference. It would 
seem that the advantage, if any, was 
in favor of bulblets from the small 
stock as it is well known that the 
younger the stock of a given size the 
better and stronger it is. 
We have submitted this question to 
a Holland grower of experience and he 
writes about as follows : 
“ In Holland everyone likes to have 
bulblets from bulblet grown stock, 
because it not only germinates better, 
but makes healthier bulbs than bulb- 
lets from old corms. I know this my- 
self from experience, and this year in 
planting bulblets from bulblet grown 
stock of America, Panama, Halley, 
Mrs. Francis King, Niagara, Schwaben, 
Prince of Wales and Glory of Holland, 
I secured some remarkable increase. 
Over 60% of this bulblet grown stock 
was one inch or more, and all bulblets 
from bulblet grown stock that were 
planted. This surely does not show 
weakness.” 
Next month we will have something 
to say on the subject of shipping per- 
ishable goods by Express or Parcel 
Post. Many growers of flower stocks 
do not properly pack their goods for 
shipment and much damage is caused 
thereby. 
T HE GARDENER frequently finds it 
necessary to bring his plants into 
shape or otherwise modify them by 
removing various twigs and branches. 
As a matter of fact a number of 
economic plants, such as grapes and rasp- 
berries, will not produce full crops unless 
subjected to an annual pruning of this 
kind. Opinions differ as to whether all 
plants are benefited by such treatment. 
Conifers when standing alone should never 
be pruned, for the branches rising from the 
ground in pyramidal form prove one of their 
chief attractions, but when used for hedges, 
as several species are, they may be sheared 
into almost any form desired. Lilacs are 
other shrubs that need little, if any, pruning, 
but the great majority of our woody peren- 
nials seem all the better for an annual trim- 
ming ; indeed, the plants set the example 
themselves and yearly throw off certain 
parts unless man attends to the matter for 
them. 
One of the most interesting of the trees 
that prune themselves is the well known 
cottonwood of the Middle West, represented 
elsewhere by its variety the so-called Caro- 
lina poplar. In late winter and early spring 
one may often find the ground beneath such 
trees fairly covered with small branches cut 
off by the tree. Hasty observers may jump 
to the conclusion that the winds of winter 
have broken off the twigs, but an examina- 
tion will show that they have been as neatly 
cut off as one could do it with a knife. The 
tissue that cuts off these twigs is known as 
a cleavage plane or abscission layer. Under 
certain conditions it grows across the point 
of attachment and, being brittle, the fall of 
the twig results. The interesting feature of 
this operation is that it is the living and not 
the dead twigs that are pruned and though 
many twigs of the preceding season are thus 
removed specimens that have been growing 
for several seasons are found with the oth- 
ers. In this tree in particular it is easy to 
determine the age of the twig because the 
heavy bud scales falling off in spring leave 
a circular scar which plainly marks the end 
of a year’s growth. Possibly a majority of 
our forest trees have this same habit of self- 
pruning, though in most cases it is less 
noticeable. 
Another form of self-pruning that is prac- 
tically universal is that connected with the 
fall of the leaf. This phenomenon is very 
familiar in our broad-leaved trees, which an- 
nually cast and renew their leaves. As is 
the case of the twigs, an abscission layer 
forms across the leafstalk or petiole and in 
compound leaves across the stalks of the 
leaflets as well. Frost does not cause the 
leaves to fall, as many people suppose, though 
the weight of the accumulated frost upon them 
may hasten the fall in some instances. That 
frost is really not the cause of leaf fall is 
shown by the behavior of tropical trees, 
which cast their leaves as regularly as 
those nearer the poles though they are 
never exposed to frost. Leaf fall in the 
tropics, however, presents a remarkable 
difference from the same phenomenon in 
temperate regions in that it does not occur 
in all trees at the same time. It depends 
upon the individual. One tree may throw 
down its leaves just as another near by is 
putting on a fresh dress ; indeed, the differ- 
ent branches of a single tree may act thus, 
one or more resting while others are in full 
leaf. It is commonly believed that the ever- 
green trees do not cast their leaves, or, at 
least, do not cast them annually. This in a 
measure is correct. Some species cast their 
leaves annually, but others hold them for from 
five to ten years. The limit in this line is a 
remarkable plant of West Africa known as 
welwitschia This species has only two 
leaves, each of which is several feet long, 
and these are retained during the life of the 
plant, which may run to fifty years or more ! 
The most noticeable form of self-pruning in 
spring is that by which superfluous blossoms 
and young fruits are thrown off. Many 
plants appear to bear more flowers than 
could be supported by the tree if all should 
produce fruits, and when too many fruits set 
the surplus is promptly thrown down Sev- 
eral parts of the flowers, the petals and 
stamens for instance, are temporary struc- 
tures useful for only a short time to the 
plant. When these have finished their use- 
fulness they are cut off in the same way that 
leaves and twigs are. Ripe fruits fall from 
the trees for the same reason, and the shed- 
ding of bark, flake by flake, or in some cases 
in larger particles, may be included in our 
category. 
There are a few plants in all climates that 
apparently have not acquired the habit of 
self-pruning. Most of the palms are un- 
able to throw off their leaves, and when 
these have survived their usefulness they 
gradually die and hang down beneath the 
crown of living green. Some of the oaks of 
more northern regions have the habit only 
partly developed and retain many of their 
leaves until spring, when they are pushed off 
by the springing leaves of next season’s 
crop. Certain fruits also remain on the 
bare branches through the winter, though 
this seems to be in some way connected with 
seed distribution, for when spring comes 
these fruits are thrown down as they are in 
other forms. 
P. Vos & Son, New Gladiolus Firm. 
Mr. P. Vos, well-known Holland Gladiolus 
Specialist and Hybridizer, of Sassenheim, 
Holland, who for many years has sent his 
catalogues to the United States and Canada 
under the name of Firma P. Vos Mz., came 
to America in the early spring of 1919, 
bringing with him his entire stock of Gladi- 
oli, a fine collection of hybrids and varieties 
of American, English, Holland, and German 
origin. 
He associated himself with The United 
Bulb Co., Mt. Clemens, Mich., where his 
stock was planted. Together with the col- 
lection of the United Bulb Co., his seedlings 
and hybrids were exhibited at the Florists’ 
Convention, held at Detroit, Aug. 19-21, 
where the Vos named varieties drew special 
attention. 
This fall, of 1919, he has separated from 
said firm and associating with his eldest 
son, Mr. Gerrit Vos, who has lived in the 
United States for a number of years, now 
wishes to introduce himself to his American 
friends and clients. All correspondence 
must be sent to P. Vos & Son, Mt. Clemens, 
Michigan. 
Mr. P. Vos has for many years paid much 
attention to the crossing of Gladioli, en- 
deavoring to obtain new varieties, stronger 
in growth and purer of color than many so- 
called leading trade varieties of today. 
Every one that knows about Gladioli and 
who attended the Gladiolus Exhibition at 
Detroit will have seen that his painstaking 
labor has not been in vain. Some of the 
varieties originated by Mr. Vos have already 
attracted much attention among Gladiolus 
growers and the firm has large stocks of 
other varieties of merit besides the Vos 
originations. 
Don’t overlook the very desirable 
varieties of Gladioli offered in collec- 
tions in this issue. 
