Sean P. O'Neill
Project Topic / Abstract:
"A Comparative Light and Electron Microscopical Study of Anther and Pollen Morphology of the Podostemaceae"
The Podostemaceae is a tropical family of aquatic
angiosperms that grow attached to rock substrates in
freshwater streams and waterfalls. Due to their specialized
habitat, plants exhibit several unusual features unique to
the family. The majority of research conducted on the family
has focused on documenting vegetative characteristics.
Considerably less information is known about the
reproductive morphology of the Podostemaceae. In particular,
palynological data have primarily been gained from light
microscopic analyses, and the pollen of only six species
from Western India have been examined. In this presentation,
pollen and anther morphology from four new-world genera are
described using scanning electron and transmission electron
microscopy, as well as light microscopy. The pollen of
Marathrum, Oserya, Tristicha, and Vanroyenella is compared
with regard to size, shape, surface ornamentation, aperture
type and structure, and wall infrastructure. Regarding
anther structure, the morphological characters examined
include the following: number and size of anther wall
layers, tapetum type, nature and density of endothecial
thickenings, and extent of connective. These morphological
data are discussed as they relate to evolutionary and
taxonomic interpretations of the Podostemaceae.
Significantly, pollen characters support classifications
that segregate Tristicha from other members of the family.
This is the first study to utilize electron microscopy in an
evaluation of pollen morphology for any new-world taxa.
Publications:
1997 Aquatic Botany 57: 133-150.
Abstract
2000 Grana 39: 221-225. Abstract
Presentations:
1994 Truman Undergraduate Research
Symposium (Kirksville, MO)
1995 National Conference on Undergraduate
Research (Schenectady, NY)
1995 Tri-Beta Biological Honor Society
Regional Meeting (Steelville, MO)
1995 Truman Undergraduate Research
Symposium (Kirksville, MO)
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