THE MOST IMPORTANT SPECIES. 



21 



These dry stems are not iinlike the woody base, which always carries 

 less rubber than the green middle portions. 



Table 1. — Chemical analyses of Asclepias aubvlata.^ 



No. 



Place of collection. 



Date of 

 collection 



Part of plant 

 analyzed. 



Acetone 

 extract. 



Rubber 

 (benzene 

 extract). 



892 

 954 



955 

 956 

 957 



958 

 971 



997 

 1011 



1015 



1120 



1121 



1122 

 1123 



1125 



1126 



1127 



B7 



B8 

 B9 



BIO 



Bll 



Near Yuma, Ariz . 

 Sentinel, Ariz. * . . . 



.do. 

 .do. 

 .do. 



.do. 

 .do. 



Imperial Valley, Calif . 

 Sentinel, Ariz 



.do. 



Tinajas Altas, Ariz. '.,.. 

 Near Dome, Ariz. * 



.do. 



Near Picacho, Calif. 



Sentinel, Ariz. 



do 



Yuma Mesa, Ariz. 

 Near Dome, Ariz. 



.do. 

 .do. 



.do. 

 .do. 



Oct. . . 

 Sept. 29 



■do... 

 do... 

 .do... 



...do... 

 May . . 



May 5 

 Apr. 3 



Sept. 29 



Mar. 19 



Oct. 18 



Oct. 18 

 Dec. 5 



Sept. 29 



Sept. 29 

 Jan. 19 

 Jan. 30 



.do... 

 .do... 



.do... 

 .do... 



Stems 



Stems 



Base 



Stems 



Stems 



Stems without bark 



Stem-bark 



Stems 



Young stems 



Old stems 



Stems 



Young stems 



Old stems 



Young stems 



Woody base 



Upper half 



Lower half 



8-inch tips 



Next 12 inches 



Lower part 



Base 



Entire stem 



Tops 



Middle 



Base 



Tips 



Next below 



Lower part 



Base 



Top 



Middle 



Base 



Top 



Middle 



Base 



Top 



Middle 



Base 



Upper half 



Lower half 



Top 



Middle 



Base 



Upper half 



Lower half 



Top 



Middle 



Base 



P- 



14 

 5 

 4 

 7, 

 9, 

 6, 



16, 

 8. 

 9. 



10. 



14. 

 9. 



10. 



14. 

 4. 



16. 



15. 



14. 



14. 

 9. 

 8. 



11. 



18. 

 16. 

 12. 

 11. 

 16. 



10. 

 14. 

 16. 

 14. 

 16. 

 16, 

 11, 

 16, 

 13, 

 18, 

 16, 

 15 

 17 

 17 

 18 

 15 

 10 



p. ci. 

 5.2 

 2.1 

 0.5 

 2.6 

 4.4 

 1.7 

 5.6 

 3.5 

 0.8 

 2.5 

 3.3 

 1.8 

 2.5 

 6.5 

 1.3 

 5.4 

 2.1 

 5.4 

 2.5 

 1.9 

 0.8 

 3.9 

 2.5 

 2.2 

 2.0 

 3.9 

 5.7 

 3.8 

 3.0 

 4.5 

 2.8 

 1.3 

 4.5 

 6.4 

 4.3 

 3.9 

 3.4 

 2.4 

 2.3 

 1.2 

 3.1 

 2.5 

 1. 

 1. 

 2. 

 2. 

 1. 



1.0 



1 In this and in all following tables the acetone extract includes the resins and other acetone- 

 soluble substances, whereas the benzene extract is taken to represent the Eunount of crude rubber, 

 although a negligible amount may have been extracted with the acetone (see p. 14). With 

 few exceptions the percentages are based on absolutely dry weight of the plant parts analyzed. 



» Growing in depression. ' From granite slope. * Estimated weight, 27 pounds, green. 



