The Causation of Variegated Leaves 
THE majority of mature plants are dependent en- 
tirely upon their leaves for the formation of 
organic matter from inorganic — a function 
which, with the exception of some of the bacteria. 
is confined exclusively to the substance called chlo- 
rophyll, which gives the green color to the leaf. The 
"1 
EUONYMUS JAPOXICUS VAR, 
REO-VARIEGATUS. 
AU- 
GOLDEN CLUB MOSS (SELAGI 
NELLA KRAUSSIANA). 
tremendous importance of this ability to convert the 
simple inorganic substances, carbonic acid and water, into 
a complicated organic substance readily transformed into 
a carbohydrate, like starch, makes chlorophyll one of 
the most "fundamental products of nature. Consequently, 
any condition which interferes with the 
normal formation of "leaf green" is of 
serious import to the plant, and the oc- 
currence of white or variegated leaves is 
an interesting phenomenon, worthy of 
study. It is a well-known fact that, with 
very few exceptions, sunlight is necessary 
for the production of chlorophyll, and 
plants grown in the dark are always 
yellowish, due to the more or less complete 
absence of this green substance. It is not 
this type of bleaching, however, which is 
to be discussed, but rather the mottling, 
striping, white edging, etc., so commonly 
seen in the leaves of cultivated plants 
growing under normal conditions. 
Most of these variegated varieties have 
originated from cuttings made from 
branches showing this peculiarity, or from 
plants which have suddenly, for no par- 
ticular reason, so far as the ordinary 
observer could detect, produced leaves 
with white markings. One might very 
properly ask what has caused "a plant, 
normally green, to develop conspicuous yellow or white 
areas, although growing in direct sunlight. Why is it 
that some plants have branches with green foliage, while 
other branches bear variegated leaves? Why is a leaf 
spotted with yellowish or white patches instead of being 
of one color? While all of these questions cannot be 
answered with absolute certainty careful study has de- 
veloped some interesting facts concerning this variega- 
tion, or chlorosis, as it is technically termed. 
For instance, we know that iron and magnesium salts 
are necessary to the formation of chlorophyll, and that 
without these chemicals plants will become colorless and 
may eventually die. Again, some types 
of variegation take place only in the sun- 
light, and the mere transfer of the plant 
to a shady place enables the new leaves to 
lie of the normal green color. Injuries 
likewise produce chlorosis of different 
types, and instances of bleaching in cab- 
bage, parsley, and similar garden crops 
which have been nipped by an early frost 
are common. Damage induced by insects 
or unfavorable conditions of the soil may 
also cause leaves and tender stems to lose 
their green color, although yellowing due 
to injury, lack of food, etc.. is in general 
very different from what we ordinarily 
term variegation or true chlorosis. 
Baur, a German botanist, has obtained 
some interesting results by grafting scions 
from certain variegated plants on stocks 
or normally green varieties of the same 
species. He demonstrated that in some 
cases stocks thus grafted would later pro- 
duce variegated foliage, and he con- 
sequently believed that the cause of the variegation in 
the scion is transmitted to the stock. 
There seem to be two distinct forms of chlorosis, how- 
ever, the one, infectious, and the other, non-infectious, 
since with some plants it is impossible to produce any 
\ VARIEGATED PRIVET (LIGUS- 
TRUM OVALIFOLIUM VAR \l' 
REO-MARGINATUM). 
BOUGAINVILLAEA GLABRA VAR. 
SAX DERI AX A VARIEGATA. 
effect on the stock, even though it be grafted with a 
variegated variety, and one plant ( Euonyiiuts japouiats) 
was found to possess both the infectious and non-infec- 
tious forms. It is likewise true that some varieties are 
immune to the infectious chlorosis which is readily trans- 
ferred to other closely related forms. Among the plants 
