A NEW COMPASS PLANT. 



By Lester F. Ward. 



THERE are few better known weeds on our great plains than 

 Lotus Ainericamts (Nutt.) Bisch., which has until recently 

 gone by the name of Hosackia Pursliiana Benth. 



I had in my camp during the past season's geological 

 campaign in southwestern Kansas two students from Southwest 

 Kansas College, Messrs. Mark and Paul White, whose home is in 

 Reno county, and who are studying botany as part of their college 

 course. They informed me that there was a plant very abundant in 

 Reno county, which always grew flat, the branches projecting in 

 exactly the opposite direction from the stem, presenting a peculiar 

 appearance like lattice-work, and that moreover these branches always 

 extended north and south, so that they could depend upon the plant 

 in getting their direction. I asked them by all means, if they saw 

 this plant, to bring me a specimen, and in a few days they succeeded 

 in doing so. It proved to be tlie Lotus Ajiicrieanns, and I found that 

 they had not exaggerated their statements. I had already seen and 

 collected the plant, but had failed, as I suppose all others have failed 

 before, to observe this phenomenon. I immediately hunted it up in 

 the vicinity and was able to examine thousands of specimens under 

 diverse conditions. The opposite or distichous character of the 

 branches is a universal fact under whatever conditions the plant may 

 grow, but the orientation varies according to circumstances. Cases 

 could be found in which some of the plants stood east and west, or at 

 any other angle, but these were usually where many were growing 

 close together shading one another, or where other plants, or rocks, 

 or trees, were present to disturb the situation. This, however, is 

 nothing more than what we find to be true of all compass plants. 

 They must be more or less isolated and situated so that the sun can 

 exert its normal influence upon them during the entire day, otherwise 

 they will not be exact indices of direction. 



Wherever the Lotus Americaniis was thus situated the branches 

 were developed on the north and south sides of the stem only. These 

 branches are alternate and not opposite in the strictly botanical sense 

 of the term, but being arranged on the opposite side of the stem only, 

 they may be characterized as distichous. 



We have then in this plant another example of a true compass 

 plant, but involving an entirely different principle from that of the 

 Silpliiuin laeiuiatuin L., Lactiica scariola L., etc., in which it is the 

 leaves and not the branches that are effected. 



