Chemical constituents and energy content of two milkweeds,Asclepias speciosa andA. curassavica

Asclepias speciosa and A. curassavica were evaluated as potential renewable sources of chemicals for use as fuel and/or chemical feedstock. Leaves and stems of both plants were analyzed for acid-detergent fiber, acid-detergent lignin, cellulose and ash. Bomb calorimetry was performed onA. curassavica (leaves 4,590 cal/g; stems 4,219 cal/g; and latex 4,663 cal/g), andA. speciosa (leaves 4,404 cal/g; stems 4,514 cal/g; and latex 9,005 cal/g). Organic carbon inA. curassavica (leaves 41.20%; stems 41.18%; latex 48.03%) andA. speciosa (stems 45.71%; leaves 42.51%; latex 67.30%) were also determined. Major differences between the 2 plant species were in the chemical composition of the latex; A. speciosa latex contained primarily α- and β-amyrin and their acetates, and a small amount of rubber, whileA. curassavica latex is known to contain at least 50% cardiac glycoside.