THE MOST IMPORTANT SPECIES. 



35 



The small size of the plant is somewhat compensated for by the 

 abundant, crowded foUage, but the leaves are so narrow that a large 

 yield of herbage can scarcely be expected. Seemingly the only possi- 

 bility of this species taking important rank will depend upon the 

 development of larger plants under cultivation and the maintenance 

 of the unique quality of carrying as much rubber in the stems as in the 

 leaves, as will be indicated below. 



Eubber-content. — It will be noted from table 8 that all of the plants 

 analyzed came from one general locality. Little can be said, there- 

 fore, regarding the rubber-content of the species as a whole. The 

 most remarkable feature of the results here tabulated is the almost 

 equivalent percentages of rubber in stems and leaves in 3 out of the 4 

 samples. Even in the fourth the difference is not so great as is found 

 in other species. It must be added, however, that the analyses given 

 under "whole" are not of the same individual plants as those reported 

 under "leaves" for the same number. In the first two numbers the 

 leaves and stems are from the same plants in each case. The word 

 "whole" as used in the table is somewhat misleading, since the roots 

 were not included in any case. It should therefore be taken to mean 

 stems and leaves as ground up and analyzed together. The results of 

 Nos. 884 and 885 indicate that mature pla^ts contain a higher per- 

 centage of rubber than inmiature ones. This is in accordance with 

 the findings for other species. 



Table 8. — Chemical analyses of Asclepias brachystephana. 



No. 



Place of collection. 



Date of 

 collection. 



Part of plant 

 analyzed. 



Acetone 

 extract. 



Rubber 

 (benzeni 

 extract). 



801 

 823 

 884 

 885 



Las Cruces, N. Mex. *. 



do.' 



do.' 



do.« 



Sept. . . 

 ...do... 



Aug. 31 

 ...do... 



Leaves . 

 Stems ' . 

 Leaves . 

 Stems ^ . 

 Leaves . 

 Whole 5 

 Leaves . 

 Whole* 



p. ct. 

 9.0 

 7.0 



8.0 

 7.8 

 8.0 

 8.0 



p. ct. 

 2.7 

 2.9 

 2.4 

 1.7 

 2.1 

 2.1 

 2.9 

 3.0 



' Growing in pastiirea. 

 ' Other plants. 



* Same plant. ' Growing in yards. * Plants in blossom. 

 ' Plants in fruit. 



ASCLEPLA.S SPECIOSA (ShOWT MiLKWEEd). 



Description. — Plant a robust, erect perennial herb, 4 to 6 feet high; 

 roots connected by deep horizontal branches, the vertical roots 

 branched near the surface to form a crown; stems several to numerous 

 from the crown, sometimes forming clumps 5 feet or more in diameter, 



