12 
THE GARDENERS' CHRONICLE OF AMERICA 
valuable work was done through scientific expeditions 
to foreign countries, piloted by experienced plant collec- 
tors who were for the most part systematic botanists. 
These men brought back many species especially suited, 
not alone for growth under glass but in the open as well. 
Most of these earlier scientific collecting expeditions 
were from England, Germany and France, but the species 
of plants collected were sooner or later brought to Amer- 
ica, and our conservatory collections were thus en- 
riched. The painstaking work of Cesalpino, Linnaeus, 
Jussier, Gartner, and others in the classification of plants 
has been of inestimable value to present-day plant grow- 
ers, for through a knowledge of the habitat and rela- 
tionship of plants, we have gained valuable information 
of their cultural requirements, such as soil, temperature, 
light and moisture. 
In the early part of the nineteenth century many col- 
lecting expeditions were piloted by such systematic bot- 
anists as Sir William Hooker, Sir Joseph Banks, and 
others ; and the species of plants from both tropical and 
temperate sections which were found suited for growing 
under glass in this country were increased many fold. In 
later years, the work of these men was followed by many 
others, among whom were Sir Harry Veitch, Verschaf- 
felt, Engelmann. Victor Lemoine and the Vilmorins. 
The scientific work of Dr. Torrey, Asa Gray, and other 
systematic botanists has been of great value to floricul- 
ture, for many of the species of native plants they listed 
are now valuable garden species. Through the work of 
these men, therefore, our list of ornamental plants has 
been increased by introduced species from the flora of 
every part of the globe. 
While some of these plant collectors have been prac- 
tical horticulturists, they have been so educated that they 
have been enabled to conduct scientific experiments. 
They have learned to associate practice with scientific 
truth. Among such men who have been engaged in the 
work in recent years, no name stands out more promi- 
nently than that of Jackson Dawson. While Air. Daw- 
son's early education and training was largely of a prac- 
tical character, his natural instinct enabled him to do 
work of a strictly scientific nature. The results of his 
propagation of material sent him by plant collectors and 
his breeding of hardy roses have been unusual. His in- 
troduction of the Dawson Rose, W. C. Egan, Farquhar 
and Sargent roses have been valuable acquisitions in the 
floricultural list of species. His "passing on" is a dis- 
tinct loss to the horticultural world. 
A scientific collector of note in recent years is E. H. 
Wilson, the student of Japanese and Chinese species, 
whose work for the Arnold Arboretum at Forest Hills, 
Mass., is bringing to our American flower lovers such 
ornamental species of value as Lilium niyrophyllum, 
Lilium Sargentiae, Hydrangea Sargentiana, Clematis 
montana, var. rubens, Buddleia variabilis var. supurba, 
Syringa Wilsonii, and many others. The history of the 
work of these collectors and a study of their introduc- 
tion of ornamental plants is extremely interesting, but 
space will not permit a detailed discussion of these. 
Following the introduction of species of jjlants from 
foreign countries and the somewhat unnatural conditions 
under which it became necessary to grow them, the plant 
culturist began to realize the need of a thorough knowl- 
edge of the requirements of different plants as regards 
light, moisture and heat. Slowly but surely present-day 
floriculturists are coming to realize that they must have 
a better knowledge of plant structure and physiological 
processes in plant life before they can successfully grow 
plants. 
That division of botany which we know as Plant 
Physiology and which relates to the vital function of tlie 
plant, is, then, of the greatest importance to the grower 
of ornamental plants under glass or in the open. Not 
only has the scientist learned many plant secrets in this 
respect during the last decade, but he has been able to 
instruct the practical grower regarding these and to 
demonstrate that certain environmental factors, such as 
heat, li,ght, and many others, so change and modify plant 
tissue that improvement in plants may be marked. 
The results of the wonderful investigations of Hof- 
meister, Green, De Candolle and von Mohl in morphol- 
ogy ; of Robert Brown, Schleiden, Malphigi and Nageli 
in vegetable anatomy ; of Koelreuter, Sprengel, Major 
and many others in plant physiology, have taught and 
are now teaching plant growers the principles which 
underlie cultural practices 
A thorough knowledge of the science of botany is 
therefore necessary for the successful cultivation of or- 
namental plants, either under glass or in the open, and 
the gradual development of this field through scientific 
investigation and research is constantly revealing new 
truths which closely afifect plant growth. 
X'egetable pathology has an intimate relation to the 
healthfulness of plant tissue. Study in this science by 
such men as De Barry, Wakker, Tubeuf, Unger, Hallier 
and others has revealed the character of many plant para- 
sites, and these men have given suggestions for extermi- 
nating and avoiding them. Probably the most valuable 
suggestions which have come from scientific ])Iant pathol- 
ogists in recent years are those which have shown practi- 
cal growers the importance of proper sanitary condi- 
tions in greenhouses if a healthy and vigorous growth 
is to be maintained. Since the pathologists have shown 
carnation growers that stem rot is induced by deep and 
careless planting, and that rose mildew is the result of 
sudden and pronounced atmospheric changes, there has 
been as marked a decrease in these diseases as if special 
directions for their eradication had been given. 
It has been necessary for men of science to demon- 
strate to practical flower growers that proper environ- 
mental surroundings are as essential for healthy plants 
as they are for human individuals in the home. In an 
excellent paper delivered by Prof. E. O. Pippin before 
the New York Federation of Floral Clubs during Farm- 
ers' Week, Professor Pippin considered the relationship 
of sanitary conditions in the soil to healthy plant growth. 
In this paper Professor Pippin states : 
"It should always be known that the crop produced is 
competing with many other plants in the soil. We well 
recognize the importance of keeping down weeds which 
will compete with the main plant for food and moisture ; 
but we have not given so much attention to the competi- 
tion of the crop with the microscopic plants in the soil, 
the bacteria and the fungi. Instead of being a dead mass, 
the soil is teeming with life. In every grain of soil there 
may be millions of bacteria and many kinds of fungi and 
molds. These require the same food elements that the 
higher plants use, and it may frequently happen that the 
soil conditions are as well or perhaps a little better suited 
to the development of these microscopic plants, than to 
our higher jjlants, and they may gain the ascendency 
and utilize the plant food designed for the crop. 
"This idea, too, is one of the recent developments in 
soil fertility. In England, Russell and Hutchinson have 
developed many facts showing that in their soil, and 
especially in soils known to be sewer-sick, and in green- 
house soils that have come into a so-called sick condi- 
tion, there may be the development of excessive numbers 
of the very simplest animals, protozoa, which compete 
with the plant roots and with beneficial forms of bacteria. 
Thev have developed facts which indicate that any treat- 
ment which kills or reduces the number of these com- 
