Dr. Jeffrey M. Osborn

Publication Abstract

O’Neill, S. P., J. M. Osborn, C. T. Philbrick, and A. Novelo. 1997. Comparative pollen morphology of five New World genera of Podostemaceae. 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 family.

Podostemaceae, Marathrum, Oserya, Podostemum, Tristicha, Vanroyenella, Pollen, Ultrastructure, Palynology, New World.