Degree Name

Master of Science (MS)

Semester of Degree Completion

1987

Thesis Director

John E. Ebinger

Abstract

Cyanogenesis in 50 species of vascular plants collected from east central Illinois was studied by examining 10 populations of each species. Each population consisted of 30 individuals, which gave an over all sample size of 300 plants per species. Herbarium specimens from the Stover Herbarium of Eastern Illinois University (EIU) were also tested for the presence of cyanide. More than 20,000 specimens were tested for this study which included cultivated plants, introduced weeds, and native plant species. The speed and degree of the HCN reaction as well as the specific plant part tested were included to give a more specific account of cyanogenesis.

Some species examined had a very high cyanogenic frequency with most populations reaching 100% cyanogenesis. Included in this group are Coronilla varia, Cystopteris fragilis, Gillenia stipulata, Hordeum jubatum, Isopyrum biternatum, and Prunus serotina. Several other species had very low cyanogenic frequencies, such as Achillea millefolium, Avena sativa, Fragaria virginiana, Glycine max, Potentilla recta, Rosa multiflora, and Tilia americana. Arisaema triphillum, Delphinium tricorne, and Sambucus canadensis are examples of highly variable cyanogenic species. Included in this study are several important cultivated crop and forage plants. Representatives of this group are Avena sativa, Glycine max, Medicago sativum, Trifolium hybridum, T. pratense, T. repens, Triticum aestivum, and Zea mays.

In the present study 24 previously unreported species were found to be cyanogenic. Also, 26 previously reported species were examined to determine their cyanogenic frequencies. It may be concluded from this study that the frequencies of cyanogenesis are usually inconsistent within any particular species. Also, the hydrogen cyanide content is highest in young shoots and leaves, and there is a higher frequency of HCN in the native Illinois species than in cultivated and introduced plants.

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