Januaey 7, 1921] 



SCIENCE 



13 



unit of dry matter was slightly more than 

 double that of corn. In other words, a sun- 

 flower plant will consume as much water as 

 a hiU of corn. Brenchly in a recent publica- 

 tion states that weeds like mustards did better 

 when they were associated with other plants, 

 than when they were subjected to competition 

 with their own species. "Wheat is not so well 

 able to overpower the Brasdca and reduce its 

 growth as is the case with some other weeds. 

 Mustard would then, according to Brenchly, 

 even in m.oderate amounts do considerable 



Possibly in the majority of places, even in 

 the agricultural areas of the middle west, 

 there are times in which there is not enough 

 water to supply the needs of the plant. Water 

 is used by a plant in large quantities and 

 practically all of it passes off in the trans- 

 piration stream. Water being an important 

 item, its conservation is a question which we 

 must be concerned with. From the few cita- 

 tions given above we conclude that weeds do 

 considerable damage to growing crops by con- 

 suming the moisture. Knowing that trans- 

 piration or the giving off of water by the 

 aerial portions of a plant goes hand in hand 

 with the leaf area, a study in which the leaf 

 area and transpiration are measured from 

 time to time at specific intervals should give 

 us much information concerning the effect of 

 weeds upon the crop in which they are asso- 

 ciated, both in the greenhouse and in the field. 



Some preliminary work done in plant phys- 

 iological laboratory at Ames by Bakke shows 

 that the matter of transpiration by weeds is 

 an important item in crop production. In 

 these experiments wheat, oats and mustard 

 were grown together and, with one exception, 

 it was found that the total transpiration for 

 the mixed cultures is greater than for the 

 pure wheat and oats cultures. The present 

 study shows that wheat transpires during the 

 growing season more than oats. 



of taxonomic work if the ecological investiga- 

 tions are to be correctly interpreted. The na- 

 tional government in cooperation with various 

 states is spending large simis of money to 

 study soils. It is a good kind of investiga- 

 tion. The soils are carefully mapped on a 

 scale as never before. The plant is an index 

 of what the soil will produce and the aim of 

 this work is to help the farmer. I am sure it 

 does; and why should the botanists not 

 cooperate with the geologist, and the soil ex- 

 pert make just as detailed a study of the 

 plant life as the geologist does of the soil. 

 In no place in the world can this problem be 

 studied better than in the prairie states. 

 There is scarcely anything left of the great 

 prairie domain, except as we find it along the 

 right-of-way of railroads. Should not a group 

 of botanists in these prairie states study the 

 ecological and taxonomic phases of the rich- 

 est, virgin, agricultural soil in the world, as 

 Shimek is now doing for the prairie plants 

 of Iowa. What we need is a crop ecologist, 

 who after a study of the problem, can teU the 

 farmer just what crops can be grown together 

 or what crops are best suited for his soil. Let 

 us as botanists seek a closer cooperation with 

 the soil expert. 



I am reminded that Dr. Cowles in an ad- 

 dress before this section called attention to 

 the use of an ecologist to settle a legal ques- 

 tion involving a large amount of money in 

 regard to a meandered lake in Arkansas where 

 a study of the problem by the ecologist dis- 

 closed the truth that the so-called lakes had 

 been covered with trees much antedating the 

 survey made by the government. I am told 

 that in some surveys along the Mississippi the 

 government instructions are to include all 

 land to the limit of apparent line of vegeta- 

 tion. Who should determine the apparent 

 line of vegetation; the surveyor, who gener- 

 ally knows nothing about succession, or the 

 ecdlogist ? It would seem to me, the ecologist. 



ECOLOGICAL PROBLEMS 



Another phase of economic botany has 

 interested me very much, namely the relation 

 of plants to soil. This requires the best kind 



EROSION 



In a prairie state like Iowa every available 

 area has been brought vmder cultivation, or 

 the wooded areas have been turned into 



