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are the members of this family that no one except an experiencedbotanist would ever suppose them to be related. Who would eversuppose that the so-called southern moss (Tillandsia usneo’ides,Linn), which grows so abundantly upon the trees of our southernstates is classed in the same family as the pine-apple, and yetsuch is the case. In the West Indies the epiphytic bromeliadsgrowing upon the trees are very abundant and give a characteristicappearance to the. landscape. Many of these species look likesmall pine-apple plants and rest erect upon the branches of thetree, frequently in great numbers.

Another very characteristic bromeliad of the West Indies isBromelia pinguin, Linn., or the so-called "rat pine." The plantsare three or four feet high and bear a striking resemblance to thecultivated pine-apples. The leaves are rather broad-toothed andspiny, bright green, but becoming pink and red with age. The-flowers are collected into a very dense panicle, are reddish andpubescent. The fruits are separated and are as large or largerthan an ordinary plum and have a very acid taste. These plantsare used abundantly for hedges, for which they are very serv-iceable.

Aside from the pine-apple for food, the "rat pine^ for hedge,and a number of others for ornamental purposes, the familyBromeliaceae is at present of but very little economic importance.

PLANT ECOLOGY IN THE HIGH SCHOOL.BY WILL SCOTT,

High School^ Terre Haute^ Ind.This paper is limited to that phase of plant ecology which

deals with plant societies. A brief survey of the development ofthe subject will assist in getting a clearer view of this phase asit is applicable to high school work.

It has long been observed that plants grow in well definedsocieties. It has been noted, for example, that cactuses and yuccasgrow in one group, deciduous forest trees, spring annuals andcertain ferns in another; while such plants as water liliesNymphaea, Nuphar) rushes and Lagittaria former a third group.During the latter part of the last century investigations were begunto determine if possible the causes of these formations.

Iplant jEcoloos 5^

There have been four epoch making contributions, besides alarge number of other valuable papers. The first of these wasmade by Warming, in 1896. He invented the term "plant socie-ties" and said that they were determined by the water contentof the soil. He divided all plant societies into three main classes:the xerophytes, mesophytes and hydrophytes. The salt marshes,according to another basis of classification, were called halophytes.

In 1898 Schimper pointed out the important distinction be-tween edaphic and climatic factors. He showed that latitude,elevation, winds, etc., determined great regional groups, such asarctic tundras, prairies, deserts and forests; while the local varia-tion in plant grouping was due to local or edaphic factors, suchas soil, light and slope.

In that year and the year following Graebner published theresults of a laborious piece of work. He found that there wasa definite relation existing between the physical and chemical prop-erties of the soil and the species which grow upon it.

The fourth and probably the most important of the four con-tributions was that of Cowles, published in the February andMarch numbers of the Botanical Gazette for 1901, under the titleof "Physiographic Ecology of Chicago and Vicinity." In testingthe already offered theories he found that they were true, butnot sufficient to explain all the facts as he found them in the field.

He found that a peat bog was very different from a riverswamp; that the plant societies of a young limestone valley anda young sandstone valley were more alike than those of a younglimestone valley and an old one. Such observations as these ledhim to accept the factors of Graebner and Warming, but also topronounce them insufficient. After extensive studies in Tennes-see, Atlantic coast, Michigan, and his own vicinity, he reachedthe following conclusions: (1) That plant societies cannot beexplained when viewed as static things; (2) that only whenviewed as to their origin and life history do they become signifi-cant; (3) that, given a temperate and equable climate, their originand life history are closely related to the physiographic devel-opment of a region.

In explanation of this last point it may be mentioned that in

a young topography such as the recently glaciated part of north-ern Indiana, there are xerophytic hills and hydrophytic swamps

si4 School Science anb /l&atbematfcs

and lakes, with a relatively narrow mesophytic region intervening.As the processes of weathering, erosion and sedimentation act onthese hills and swamps the topography is brought nearer andnearer to planation and with this change the mesophytic zone

becomes broader and broader, while the xerophytic and hydro-phytic areas become more constricted. The climax type of a topog*raphy is planation, and that of plant formations is the mesophyticsociety. It may be noticed that as the topography advances fromone form to another the plants are displaced by species betterfitted to live in the new conditions. In any given location onegroup is imposed upon another, so that a vertical section showingthe plants found in the different stages in its development wouldgive a fairly good key to its physiographic history. These changesare not made suddenly, but are so gradual that in any plant societythere are usually remnants of a former condition and forerunnersof plants that are to displace existing ones. These societies oftenlag behind their cumulative causes; for example, when a lake isformed quite a period elapses before a typical lake flora exists.Plants march forward not in confusion, but in well defined zones.These zones have dominating plant which give them color. Themiddle of a zone is static or nearly so. The border line betweentwo zones, the zone of tension as it is called, is very significant.Here the struggle between species is very sharp. The conditionshere are not what they once were. The species which oncemaintained their supremacy are being crowded out by those whichhave been living in a similar condition just outside the zone oftension.

With this brief survey of the factors governing the origin anddevelopment of plant societies the questions to be considered are:Plow much of it is good for the high school ? Under what condi-tions can that part be incorporated in the course with profit ? Howmay the subject be presented?

In the high school only the factors worked out -by Warmingand Cowles in the water content of the soil and the physiographicfactor should be considered.’ The regional distribution is usuallyincluded in courses on physical geography. The factor whichGraebner proposed presupposes- too much knowledge for con-

sideration in a high school course.

Under what conditions is the course feasible: (1) The course

BSlant 3Ecol<>0s 5^

should be preceded by at least one-half year of general botanyand enough physical geography to give a clear notion of thephysiographic processes. If a knowledge of these laws has notbeen worked out previously their study will have to be incorpor-ated in the course on ecology. (2) A region must be availablewhere plants grow under natural conditions, as anything artifi-ficial disturbs the orderly sequence of societies. (3) A fairdegree of skill in the identification of species is necessary. (4)Conditions must be such that the major portion of the timealloted to the subject may be spent in the field. Where theteacher cannot supervise the field work in person it is possiblethat the work will be done thoroughly only by those who havebecome intensely interested in their previous study of botany.This argues that it should be made an elective.

How should the course be presented? (1) The class shouldbe divided into sections containing from two to four students.Each group should be assigned a problem and held responsiblefor it.

In the selection of areas for study the teacher should exercisethe greatest care. Level areas over which one set of conditionsmaintain should be avoided as they are valuable only in a com-parative study.

A section along a meandering stream, a bit of lake margin

with its adjacent slope, a swamp or pond would furnish an idealproblem, for here the physiographic processes are changing thetopography with such rapidity that the movement is easily dis-cerned.

I suggest that the following points be worked out and in theorder given: (1) A careful map should be made of the areaunder consideration. (2) The plants should be listed and theirlocation and relative numbers indicated on the plot. Then thezones, with their characteristic plants, should be worked out,and also the general areas, i. e., the xerophytic, mesophytic andhydrophytic areas. (3) Then the physiographic processesshould be considered. Regarding planation as the climax, is themovement progressive or regressive, or, if both are present, inwhat part of the area is each found ? (4) Then to these processesshould be related the plant zones. From that time, these zones

will not-be viewed as static things by the student, but as groups

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of species in progressive movement, their line of march beingdetermined and accompanied by the changes in the topography ofthe region. Finally all irregularities should be worked out andaccounted for.

The teachers aim should be to leave the student with a clearinsight into the dynamics of plant distribution.

HIGH SCHOOL GEOGRAPHY.BY FRED J. BREEZE,

High School, Delphi, Indiana.The lack of definite understanding as to just what geography

is, the failure of schools to provide the necessary field and labor-atory work, the absence" of special geographic training on the partoi the teacher, and the notion that any one can teach geography,all lead to the unsatisfactory condition of this science in our highschools. This paper deals briefly with some of these defects, andthen presents a few suggestions concerning a one-year course inhigh school geography.

Successful geography teaching demands that the teacher pos-sess a definite idea of the nature and aim of this subject, yet thereis too often the lack of this thorough understanding.- Consultingvarious sources one finds a bewildering difference of opinion asto just what geography is. Yet among eminent geographers ofEurope and America there is a fair agreement on this matter.Davis of Harvard, and Dryer of our own state, have been of mostservice in giving us a definite conception of geography.

Geography deals with man and his physical environment, butthe interrelations between man and his environment are not thewhole of the subject. The mutual relations among the variouselements of this environment are an essential part of it. , The re-lations between man and earth cannot be intelligently understooduntil the relations existing among the elements of environment aregrasped. These elements can be grouped under relief, climate,and plant and animal life; and the mutual relations between reliefand climate, and between relief and climate on one hand and plantand animal life on the other hand constitute the first half of geogra-phy, which is physical geography or physiography. The secondhalf includes the mutual relations between man and his material