tracings from the specimens being described will give a very accurate idea of the length, width, and cross section of the fruit or tuber. The value of uniform notes on horticultural varieties of vegetables, fruits, and flowers will at once suggest many advantages, to every seedsman, florist, gardener, and student. Such notes will enable seedsman to at once determine whether or not a so-called novelty is really new or not. If it is new and posesses any feature of special merit this will at once be brought to light. In like manner notes of a similar character will aid florists and plant breeders to identify varieties, detect variations and determine the results of different cultural practices upon vegetative growth and flower production.

To the student they will offer facilities for determining the duration and modifications which take place in varieties as well as a means for determining their geographic and soil limitations.

With each year the value of such a system will become more apparent and its uses will become more numerous and better appreciated. A great step toward securing such an end would be made were the Society for Horticultural Science to give its official sanction to the work which has already been done and authorize the present self constituted committee to continue the work it has begun or to constitute and empower a new committee to do the work. What I am interested in is to assist in accomplishing something along this line.. The co-operation of the station horticulturists encourages me to believe that the results desired will soon be a reality. We need the co-operation of horticulturists working in all lines both in this matter of horticultural records and in our general work. The work we are engaged in is general, no one man can accomplish much working alone but with earnest co-operation wonders will result.

THE RELATIONSHIP OF PLANTS IN THE ORCHARD.
U. P. Hedrick.

Agricultural College, Mich.

The relations which plants bear to their physical conditions, as soil, heat, moisture, and the like, are well understood in the main. Agriculture is and ever has been concerned with these relations. Practically all of the operations of the husbandman are efforts to help plants in their struggle against the circumstances of environment. When physical conditions are prejudicial, the life of the plant is a prolonged struggle against circumstances to which it may succumb, or under which attain a profitless maturity.

But plants are influenced by other factors than those of their physical environment. They have inter-relations between themselves upon which often depend their best development. Agriculture has neglected these relationships of plants to each other and has devoted itself almost entirely to plants and their envioronment.

The agriculturist, for most part, has looked upon plants as passive, unchangeable organisms to which it was his business only to supply certain definite external conditions as food, moisture, and a foothold.

In this connection I may remind you that a generation ago it was the fond dream of the chemist and of the agriculturist that an exact analysis of the soil, followed by a generous supply of any lacking elements, would result in fruitful harvests. I need not tell you that this dream has not been realized. To the contrary, we are depending less and less upon analyses of soils, and more and more upon a knowledge of plants, and especially of their life histories, as manifested in their needs, habits and relations. This is but one of the many illustrations of how, consciously or not, we are being led to a new conception of plants, of how we are coming to look upon them as plastic organisms capable of remodelling in all their parts and of how the agriculturist must regulate all of the conditions of plant life, external and internal, if he is to realize as completely as possible the ends for which he cultivates.

This brief introduction brings me to my subject, "The Relationship of Plants," a phase of plant life, which it seems to me, the agriculturist has neglected and the botanist has studiously avoided. The former looks upon the subject as too broad and vague for his study, and the latter, with that perversity of botanists to avoid all cutivated plants, deems it of small importance.

Wherever Nature reigns, plants grow in communities. In some of these communities, the interdependences of the individuals and of the species are so intimate that there seem to be plant organizations, the members of which share the weal and woe of the community. The beech gathers about itself the same plants in New York, Maine, or Michigan. Name the ground plants, and the forester will tell you what trees grow in a forest. Pyrolas, wintergreen berries, and huckleberries are always found with white pine. So with weeds in the field. Each cultivated crop has its motley crew of hangers-on. Does human interference entirely do these plant communities?

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What has this to do with fruit growing? The answer is that through a study of their relationships we can better determine what the vital necessities of cultivated plants are. In nature plants form communities because their necessities are the same. They are forced by their needs into companionship. So it comes that widely different species of plants often thrive side by side.

Thus a knowledge of the associations of cultivated plants, of the species, and varieties that thrive side by side, would throw new light on the inter-relations of climate and soils with fruit-growing. Note how the various communities formed by wild life characterize soils and climates, not alone of zones and countries, but of townships, localities, and even farms. In botany we give definite names to plant

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communities. We speak of this flora and of that flora, and all understand. Year by year, as these are better understood, the classification proceeds, and to the great benefit of systematic botany. Horticultural floras are just as real. We need to have them classified and named, that we may speak understandingly of them. True, something has been done in this respect in the catalogue of fruits, issued under the auspices of the American Pomological Society. Pomological districts have been created for the United States, showing homologies in climate, soil and in other important features, but there is great need of an extension of this work and in several directions.

"Theories are fascinating," you say. "In what direction will a knowledge of horticultural floras be of advantage to fruit-growing?" The catalogue of fruits mentioned could be made to show the variations of types in the regions already created; the locations of dominance of the various fruits and their varieties; locations of greatest size, highest color, best quality, and relative stability for all varieties; the longevity of individuals and of varieties in different regions; and a classification of varieties as to their likes and dislikes for various soils. A survey of horticultural regions along these lines would enable the fruit grower to specialize more closely and to plant and market his fruit to better advantage. There is no phase of horticulture of more vital importance at the present time with the keen competition that exists between different fruit regions, than the adaption of fruits and their varieties to geographical and local conditions. There should be horticultural floras established to show these adaptations.

The effects of crops and crop residues on the soil is another of the relationships of plants which imperatively demands attention. Plant life constantly changes the soil. A species may thus transform the soil favorably or unfavorably to itself as a succeeding crop, or favorably or unfavorably to other species which may follow. Thus a peach tree planted in the place of a perfectly healthy peach tree, ordinarily does not thrive. But few farm or garden crops grow well, succeeding themselves. In rotating farm crops, certain ones will not follow others advantageously, no matter how abundant the food supply may be. Our knowledge of these relationships is very vague and as the science of agriculture progresses, we must come to understand them 'better.

We do not know, for instance, to the satisfaction of all, what causes "sick" or "over-cropped" soils; or why it is that certain plants "exhaust" the soil for certain other plants; why fruit trees and some other crops do not thrive on newly cleared land following certain timbers, as the walnut and butternut; why rye grass, some of the Erigerons and some of the Vetches, as the tare, "poison" wheat. Thistles are said to "poison" oats; Euphorbias kill flax; members of the genus Inula are thought to be death to carrots; the peach and potato do not consort without mutual injury. We lay

these antipathies to competition for food, moisture and air, but every observant cultivator knows that there are other factors causing such uncongenial relations of plants.

Jones and Morse, of Vermont, record a most interesting case of antagonism existing between shrubby cinquefoil and the butternut tree. They found that a butternut tree in fields overgrown with cinquefoil occupies the center of a clear circle of a diameter equal to the spread of the tree roots. Experiments seemed to show that butternut roots were in some way attracted to the area occupied by the cinquefoil roots. The authors ascribe the fatal influence to root rather than foliage relations. Mr. F. C. Stewart, of the Geneva Station, is led to suspect from observations of his that the walnut may exercise a somewhat similar antagonism to the grape.

Nearly a century ago DeCandolle expounded his "excretory theory" to explain these incompatibilities. The "excretory theory" is now disproved of by botanists, but the above facts, which, in the main, gave rise to it, are still unexplained. Plants may not crete poisons, but may they not in some way leave residues injurious to other plants? At any rate, we are not as yet able to wholly explain the facts which give rise to DeCandolle's theory.

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Rotation of crops is a vital question in the agriculture of many countries. It is almost wholly a problem in the relationships of plants. The practice had its beginning in DeCandolle's theory that the residues left in the ground by plants were beneficial or detrimental to succeeding crops. The behavior of crops following clover was the chief fact upon which his "excretory theory" and the early systems of rotation were based. Until the discovery of the symbiosis of bacteria and the legumes, it was held that rotation was entirely a matter of soil and of food. Knowledge of the association maintained between bacteria and members of the clover family has shed more light on the rotation of crops. May not other relationships be discovered which will still further illuminate the now dogmatic practice of rotating crops?

The isolation of plants is a problem in plant relationships which we have largely settled. Thus long ago it was demonstrated in a splendid series of experiments at Rothamsted that certain species of grasses grow best when grown together and that others were positively injurious to each other when grown gregariously. On the other hand, the intensive struggle between plant and plant in many crops compels thin seeding, or the isolation of individuals that plants may attain their best development. The fruit-grower has learned, for instance, that, except under very rare circumstances, he must set his plants such a distance apart that the competition between individuals is eliminated. The law in nature is "few and mighty;" under man, "many of high average," and "a fair show for all."

We know something, but not all, about the relation of weeds to domesticated plants. Weeds are universally looked upon as enemies of the husbandman, serving only as "grindstones and whetstones to sharpen his wits." But there are lessons for the farmer and the horticulturist in the study of weeds. Thus, in the selection of crops, weed floras can be made guides as to the adaptability of soil, climate and other conditions for a given crop. A better knowledge of their relationship with the plants of the field would be most helpful in suppressing weeds. When there is food and moisture enough for all, or when the requirements of cultivated plants and weeds are distinctly different, the latter do little harm. Chickweed, which grows best in cool, damp weather after tree growth has ceased, is an excellent late cover crop for an orchard; black mustard serves the same purpose in some localities.

Perhaps in no field of horticulture is there greater need of knowledge concerning plant relationships than in the domain of plant diseases. In the past we have looked upon the rusts, smuts, mildews and their like as unavoidable scourges, foreordained by the Creator, and to be conquered only by the machine gun in the shape of a spray pump. We have seemingly entirely overlooked the relation of paracites and hosts, in which the former is an unwelcome guest of which the unwilling host makes strenuous efforts to rid itself. Plants are not passive to the attacks of parasites, a relationship which involves the whole matter of predisposition, resistance, and immunity, of which we now hear so much.

Professor H. Marshall Ward of England, in experiments with rust fungi, has clearly shown "that not only do these parasites vary and differ in their process of adaptation to different hosts in the same species or genus, but the hosts exercise definite reaction on the fungi." He concludes "that not only does the power of the fungus to attack the given species of the flowering plant depend on the specific nature of the latter, but it also depends on the specific nature of the previous host on which the spores were produced." Surely this relationship can be made use of in developing the capacity of resistance to infection in different species of plants.

In the past we have given relatively too much time to the study of the fungus and too little to the study of the host plant. We must recognize more and more the capacities of plants to combat parasites. In the future we shall largely control plant diseases by selecting and by creating resistant and immune varieties. We must discover, if possible, what factors govern resistance to disease and how they may be controlled. We must know why the best grown plants are often most susceptible to disease; why some trees in the orchard succumb more quickly to disease than others; why the same plant yields to parasites at one age or season and not at another. Is it not possible that we may know what condi