IOWA ACADEMY OF SCIENCE 131 
Silphium laciniatum L 134, 147 
Sisymbrium officinale (L.) Scop 13 
Solanum tuberosum L 15, 51, 57 
Solidla'go canadensis L. 125, 132 
Solidago serotina Ait 134 
Solidago ulmifolia Muhl 125, 132 
Solidago pinnata (Walt.) Brit 13 
Spartina cynosuroides (L.) Willd 110 
Stieronema ciliatum (L.) Raf 140 
Symphoricarpos vulgaris Michx. - 80, 133 
Syndesmon tbalactroides (L.) Hoffmg 145 
Syntherisma sanguinalis (L.) Dulac 54, 155 
Syringa vulgaris L 77 
Taraxacum taraxacum (L.) Karst 68, 107 
Thalietrum purpurascens L 73 
Trifolium pratense L. . 97 
Trifolium r,epens L 30 
Tripsaeum dactyloides L Ill 
Triticum vulgare L 104, 151 
Ulmus americana L 85 
Ulmus racemosa Thomas 85, 87 
Verbena hast at a L 74 
Verbena stricta Vent 74, 146 
Verbena urticifolia L 74 
Verbesinal alternifolia (L.) Britt 74 
Vernonia fasciculata Michx 65, 106 
Vemonia noveboracensis (L.) Willd 106, 126 
Viola papilionaoea Pursh 61 
Vitis labrusca L 2, 9, 21, 47, 83 
Xanthium canadens,e Mill 119 
Zeia mays 117, 150, 156 
