14 
THE GARDENERS' CHRONICLE OF AMERICA 
tain a quantity of food elements and yet the plant may 
starve. For this reason chemical analysis is seldom sat- 
isfactory from the grower's viewpoint. The chemist can 
determine tlie minerals which comprise the soil, but he is 
not familiar with the food requirements of plants of dif- 
ferent species and the availability for these plants of 
the minerals ami organic substances in the soil. This 
is a problem to be determined onl}- by experimentation 
for each particular crop and for each type of soil, and it 
is the function of the scientists in our experiment sta- 
tions to work out these problems for the benefit of the 
practical grower. 
The chemist is, however, teaching the flower grower 
tlie sources of plant food, and how to treat his crops so 
they will receive the proper amounts of nutrition. The 
chemist is also giving the flower grower a better knowl- 
edge of the so-called "commercial fertilizers" and their 
ettect on plant growth. 
It is impossible to discuss fully all that scientific 
chemistry has done for floriculture. The results of this 
type of work have been so far-reaching, not only as re- 
gards a plant's environment with reference to atmos- 
phere, soil and its fertility, but along the lines of in- 
secticides and fungicides as well. We know that sanitary 
conditions in the home have much to do with keeping 
disease germs and insect pests from gaining a foothold ; 
nevertheless, contagion sometimes spreads from less care- 
ful individuals in the human family. The same principles 
appl\- with plants, especially in greenhouses. The scien- 
tific chemists have solved many a complex problem for 
the florist in the eradication of both insects and fungi 
on plants. 
In this work the chemist has been assisted in a con- 
siderable degree by the entomologist and the plant 
pathologist. The work of the entomologist has been to 
studv the character and the life history of different 
groups of insects injurious to plant life, and through 
this intimate knowledge to aid the chemist in compiling 
formulas of sufficient strength to exterminate the pest. 
As certain chemical substances are injurious to plant 
issue, the scientific work of the plant physiologist has 
also been necessary to bring about methods of insect ex- 
termination by the use of chemical substances, which 
are effective and which are in no way detrimental to 
tlie vigor of growth of plants. 
A question has sometimes arisen in various depart- 
ments of agricultural colleges regarding the value of a 
knowledge of physics. One of the fundamentals of plant 
growth is light intensity, and I consider physics a most 
important subject for all students in floriculture. The 
science of physics has been of great value to the florist, 
but it might be much more so if some enthusiastic 
student would perform his experiments on light intensi- 
ties in greenhouses, and demonstrate the influence of 
diflr'erent light intensities on different types of plant 
growth. We know in nature that there are many species 
of plants which are light demanding ; others are shade 
enduring and even shade demanding. We usually con- 
sider that it is necessary that greenhouse plants obtain 
all the sunlight possible. This is, in general, true for 
most plants, but others demand some shade. The per- 
centage of light under which jilants make their best de- 
velopment is still a matter of conjecture. The physics 
of light, however, has been studied, and science has 
demonstrated the possibility of building greenhouses 
with the pitch of the roof at such an angle that the 
maximum amount of sunlight will be available. 
It is impossible to properly demonstrate in a single 
article all that science has done and will do in the future 
to develop the art of flower and plant production. As 
has been stated, the necessity for an application of 
scientific principles to floriculture has been of compara- 
tively recent origin. As competition increases in the 
world of flower production, there is sure to be a greater 
demand for scientific information, and the field of in- 
vestigation is broad. There is a constantly increasing 
demand for men in the flower producing industry, who 
have had broad, scientific training. These men are to 
become in the future America's foremost flower 
producers. 
EUPATORIUMS FOR THE GREENHOUSE. 
'TPHE genus Eupatorium is an extensive one, consist- 
ing of some 400 species. Some, which are natives 
of North America, are hardy, but many that occur in the 
warmer districts require the protection of a greenhouse, 
llieir flowering season extends from the autumn till the 
spring, and all are extremely prolific in the production 
of blossoms. 
The first to flower is E. riparium, a loose-growing 
shrubby plant with a profusion of small white flowers, 
disposed in open clusters. Close after it, as a rule, or 
occasionally even in front of it, comes E. odnratissinnini 
(or Weinmannianum), a far more upright, compact- 
growing plant. 
Next to these in time of flowering comes E. petiolare, 
and from my point of view this is the best of all. It 
makes a bushy plant from 2 feet to 5 feet in height, and 
the flower heads are very suggestive of a single daisy 
in the bud state, being pink in the center and white 
towards the edges : after a time the petals protrude from 
the disc, and impart a fluft'y appearance to the flower 
heads. Individually the latter are about half an inch 
in diameter, white or nearly so when fully expanded, 
and borne in branching corymbs. They have a very 
agreeable perfume, and last well in water. The plant 
is of cut-and-come-again character. Apart from its use 
in this way, the eupatorium in question is verv orna- 
mental as a flowering specimen. 
E. adenophorum ( another name for which is E. tra- 
pezoideum) is a larger grower than the preceding, but 
if pinched freely good examples may be obtained from 
4 to 5 feet in height, and nearly, if not quite, as much 
tlirough. The individual flower heads of this are about 
one-third of an inch across, and borne in flattened 
corymbs 4 inches or so in diameter. As a rule, this 
flowers during the latter part of the Winter and in early 
Spring. 
Soon after Christmas the blossoms of E. vernale ex- 
pand. This does not attain anything like the dimensions 
of the preceding, but is much valued as a pot plant, as 
it will flower freely when about 18 inches high. The 
blossoms are white, and borne in loose clusters. 
As spring advances the lilac-colored blossoms of E. 
( Hebeclinium) ianthinum, a good deal like an enlarged 
ageratum, put in an appearance, as also do those of the 
deeper-tinted E. atro-rubens. These make good pot 
plants, and are in this way more useful than for cutting 
from. 
The culture of these Eujiatoriums is very simple, as 
they readily strike from cuttings in the spring, and grow 
away freely afterwards. The Summer treatment given 
to chrysanthemums will suit them well, as they are at 
that season better outside than under glass. As the pots 
become well filled with roots an occasional stimulant is 
very beneficial. Spring-struck cuttings may be flowered 
in pots 6 inches or more in diameter. — The Gardeners' 
Magazine (English). 
