THE MOST IMPORTANT SPECIES. 



23 



Since this is a species of rich, moist bottom-lands, it is probably not 

 suited to arid conditions. If this assimiption is correct, Asclepiaa 

 sullivanti would seem to hold but little promise of success as a cultivated 

 plant, since, regardless of the amount of rubber it might yield, other 

 crops could probably be grown at a greater profit. However, the adapt- 

 ability of the species to other soils and the variation in rubber-content, 

 which would undoubtedly accompany such a change of habitat, are 

 matters which should be tested experimentally, for this is in other 

 respects one of the most promising of. all of the milkweeds thus far 

 examined. The tall-growing erect habit of A. sullivanti is much in its 



Table 2. — Chemical analyses of Asclepias sitllivanti. 



No. 



Place of collection. 



Date of 

 collection. 



Part of plant 

 analyzed. 



Acetone 

 extract. 



Rubber 

 (benzene 

 extract). 



387 

 817 

 886 

 1016 

 1017 

 1018 

 1019 

 1020 

 1021 

 1022 

 1023 

 1024 

 1025 

 1026 

 1027 

 1028 

 1029 

 1030 

 1031 



Lincoln, Nebr 



Ellsworth, Kane.'. 

 Lincoln, Nebr. ' . . . 



do 



do.' 



do.» 



do.' 



do.* 



do.« 



do.' 



do 



do.« 



do.» 



do.' 



do.' 



do.' 



do.' 



do.' 



do 



Aug. 9 

 Sept. . . 

 Aug. 2 

 Aug. 28 

 ...do., 

 do.. 

 ...do.. 

 ...do.. 

 ...do.. 

 Sept. 6 

 ...do.. 

 ...do.. 

 Sept. 14 

 ..do.. 

 ..do.. 

 Sept. 22 

 ..do. 

 ...do. 

 Sept. 12 



Stem8 . . 

 Leaves. 

 Stems. . 

 Leaves. 

 Stems.. 

 Leaves . 

 Stems. . 

 Leaves . 

 Stems . . 

 Leaves. 

 Stems. . 

 Leaves . 

 Stems.. 

 Leaves * 

 Stems. . 

 Leaves . 

 Stems . . 

 Leaves. 

 Stems . . 

 Leaves* 

 Stems . . 

 Leaves . 

 Stems.. 

 Leaves . 

 Stems.. 

 Leaves. 

 Stems.. 

 Leaves . 

 Stems.. 

 Leaves. 

 Stems.. 

 Leaves. 

 Stems.. 

 Leaves. 

 Stems.. 

 Leaves * 



p. d. 

 8.7 

 6.2 



9.5 

 6.0 

 9.4 

 6.3 

 8.6 

 6.7 

 8.6 

 7.8 

 7.1 

 7.0 

 8.1 

 4.7 

 7.7 

 7.1 

 7.3 

 6.4 



10.6 

 9.3 

 8.2 

 1.2 



10.9 

 6.4 

 9.9 

 2.3 



11.7 

 6.1 

 7.9 

 4.3 



10.0 

 4.6 

 8.1 

 1.9 

 7.9 



p.et. 

 6.1 

 0.4 

 6.0 

 8.2 

 8.1 

 0.2 

 6.4 

 0.6 

 3.0 

 0.2 

 1.2 

 0.9 

 3.0 

 0.9 

 3.6 

 0.4 

 4.0 

 0.2 

 4.1 

 0.2 

 2.7 

 0.5 

 2.0 

 0.3 

 2.7 

 0.4 

 3.6 

 0.3 

 4.2 

 0.2 

 3.0 

 0.2 

 4.2 

 0.6 

 4.2 

 0.1 

 2.3 



1 Plants injured by frost and leaves with 



more blackish patches. 

 * Verified by 6 duplicate analyses. 

 ' Same locality as 1016. 



* From 5 plants. 



' Five plants from same spot as 1020. 

 ' Five plants from same spot as 1021. 

 ' Five plants from same spot as 1023. 



