REPORT OF PLANT PHYSIOLOGIST. 



F. E. Lloyd. 



Dr. C. C. Thach, 



President Alabama Polytechnic Institute, 

 Auburn, Alabama. 

 Sir: 



I bef^ leave to submit the following annual report as 

 Plant Physiologist of the Alabama Agricultural Experi- 

 ment Station, being a report of the second complete year of 

 my tenure of that office. 



"a year ago, I stated that the preparation of my mono- 

 gra!)h on the guayule, (Parthenium argentatum), a desert 

 rubber plant of Northern Mexico, was completed. This 

 will shortly appear as Publication 139 of the Carnegie In- 

 stitution of Washington. As a logical continuation of this 

 work, the guayule and several of its congeners are being 

 studied continuously in their relation to soil and climatic 

 conditions at Auburn, while, at the courtesy of the Carne- 

 gie Institution of Washington, two of the species, the 

 guayule and the mariola, are under observation at the 

 Desert Botanical Laboratory. Tucson, Ariz. The data ac- 

 cumulating will afford material for a study of acclimatiza- 

 tion. 



My study of the development of the fruit of the date 

 (Phoenix dactylifera), begun as a portion of an Adams 

 Fund project at the Arizona Agricultural Experiment Sta- 

 tion, has been completed. One of the primary objects of 

 this study was to gain light on the role of tannin, which in 

 this fruit and in the persimmon is a predominant factor in 

 its relation to the ripening process, but the behavior of 

 other foods (starch, reserve cellulose, oil especially) were 

 also studied, during the whole embryonic period. Among 

 the results of major interest, it was found that, judging 

 from their physiological relations, there are two kinds of 

 tannin ; one being used as a food material, probably for the 

 building up of the reserve cellulose in the endosperm, 

 thus affording support to the recently-published view of 

 van Wisselingh based on Spirogyra; the oiher is not a 

 plastic material, but is secreted within certain cells of the 

 seed coats and carpel where it remains permanently, after 

 the fashion of an excrete. 



