Date of Award

7-1975

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Dr. C. Gehris

Comments

The pollination ecology of four populations of vernal herbaceous angiosperms representing four locally common species of plants in the Central New York State area were studied. Three study sites were selected and research was conducted in the field by personal observation and accepted experimental methods. Four experimental categories were established for each species at their study sites. One group of plants represented controls, the second groups had their anthers excised at anthesis, the third were isolated from foreign pollen by placing them in plastic bags and the fourth were both isolated and emasculated.

By controlling pollen influx in each category, the main mode of reproduction could be determined on the basis of fruit and seed production. Visiting insects were captured on blossoms, checked for the presence of host plant pollen and identified to species (in most cases).

Hepatica acutiloba DC. showed a trend towards xenogamy favoring an entomphilous syndrome although a small percentage of seeds appeared to be produced by autogamy through a mechanical syndrome. Short-tongued flies and solitary Apoidea were common pollinators. Erythronium americanum Ker. Also showed a trend towards xenogamy, but pollination was accomplished by large heavy Apoidea. Trillium grandiflorum (Michx.) Salisb. is agamospermic, but not unless abortive tubes are produced in the pistil. Under experimental conditions in the field, pollen deposition on the stigma was the result of an entomphilous syndrome that appeared to favor xenogamous transmission. Podophyllum peltatum L. was the only species studied, which reproduced entirely without insect vectors. Fruit production was the result of successful agamospermy. In other populations P. peltatum may be a typical xenogamous Bombus pendant flower, but agamospermy appears to dominate the Brockport population, which seems to be the result of intraspecific competition with invasive field species.

The morphology, phenology, and ecology of the four species studied reflected the coevolution of blossoms and vector. Discrepancies existed between the biology of the populations and the information present in some field guides, suggesting that environmental barriers result in different evolutionary trends between populations.

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