Dr. Jeffrey M. Osborn
Dean of the School of Science and Professor of Biology
The College of New Jersey
O’Neill, S. P., J. M. Osborn, C. T. Philbrick, and A. Novelo.
1997. Comparative pollen morphology of five New World genera of
Aquatic Botany 57: 133-150.
The Podostemaceae are the largest family of strictly aquatic angiosperms;
however, relatively little is known about the palynology of the family.
Pollen micromorphology and ultrastructure of five representative New World
taxa are described, including Marathrum rubrum Novelo & Philbrick, Oserya
coulteriana Tul., Podostemum ceratophyllum Michx., Tristicha trifaria
(Bory ex Willd.) Sprengel, and Vanroyenella plumosa Novelo & Philbrick.
Pollen grains from all five species are relatively small, spherical,
microechinate, have a tectate-granular sexine and a thick nexine in
non-apertural regions, and a semitectate sexine and a thin nexine in apertural
regions. Characters that vary among the taxa include dispersal unit (monads
or dyads), sculptural element morphology, infratectal granule size, and
aperture morphology and ultrastructure. This is the first study to describe
the pollen morphology these five taxa in detail, and it is the first to
illustrate the ultrastructure of pollen wall characters for any member of the
Podostemaceae, Marathrum, Oserya,
Podostemum, Tristicha, Vanroyenella, Pollen, Ultrastructure, Palynology,