Table 1. --Numbers of rootlets on main laterals by diameter and distance from main trunk 



Root 

 diameter 













Distance from main trunk (feet) 











Total 



[ Distributior 



(inches) 



0-5 



5-10 



10-15 



15-20 



20-25 



25-30 



30-35 



35-40 





50-55 



55-60 



60-65 



65-70 '. 





















- Number - - 















Percent 



0.10-0.25 



249 



311 



198 



113 



29 



29 



68 



63 



37 17 



23 



14 



13 



43 



1 ,207 



84. n 



.26- .50 



43 



38 



14 



11 



6 



5 



7 



5 







2 







131 



9.2 



.51-1.00 



26 



11 



8 



4 



1 



4 



1 



2 



1 











58 



4.1 



1. 10-1.50 



15 



3 



1 























19 



1.3 



1.60-2.00 



8 



























8 



.6 



2.10-2.50 



1 





























_ 2 



2.60-3.00 



2 



























;} 



Total 



344 



363 



221 



128 



36 



38 



76 



70 



38 17 



23 



16 



13 



43 



1 ,426 





Percent 



24.1 



25.5 



15.5 



9.0 



2.5 



2.6 



5.3 



4.9 



2.6 1.2 



1.6 



1.1 



.9 



3.0 





100.0 



4. Close to 50 percent of secondary laterals were within 10 feet of the tree 

 stem, 65 percent within 15 feet, and 75 percent within 20 feet. Similar relations have 

 been recorded for Scots pine (Kalela 1954). Moisture measurements made at the end 

 of the growing season in a 16-year-old loblolly pine plantation suggest that tliis species 

 has a similar pattern of rootlet density. Available soil moisture was greatest at points 

 furthest from the stems and lowest a few inches from them (Douglass 1960). 



5. Lengths of main laterals varied from 45 to 797 inches; three exceeded 700 

 inches, and eight exceeded 200 inches. 



6. The total of live main lateral root lengths was 4,801 inches. 



7. Most of the sinker roots were within 3 feet of the stem (see fig. 1). 



8. In addition to the main laterals (fig. 1), 19 other roots emanated from the 

 main root collar. All of these were less than 3 inches in diameter; 14 were less than 

 one -half inch in diameter , and none were of significant length. They may well have 

 been adventitious roots. 



The taproot of Pinus ponderosa is believed to have four xylem strands and the 

 lateral roots may have two, three, or four.'^ Because secondary laterals usually 

 originate opposite these xylem strands, and because in this instance the roots are 

 assumed to be triarch, figure 1 in plan shows only two-thirds of the total root tally 

 and in elevation only one -third. 



According to Dr. K. Esau, Department of Botany, University of California, 

 Davis, California, through courtesy of Dr. N. T. Mirov, formerly with the Pacific 

 Southwest Forest and Range Experiment Station, Berkeley, California. 



5 



