Research Training Program

Susan Aragon
Universidad Nacional San Antonio
Abad del Cusco
Cusco, PERU

W. John Kress, Ph.D.
Project Advisor
Department of Botany

"The RTP is a great opportunity to increase our scientific knowledge and develop a whole vision about how a major natural history museum functions. Interactions with students from different backgrounds further enriched this experience."

Systematics Implications of Pollen Morphology in Heliconia (Sections Tortex and Farinosum)

Tortex fits in the Farinosum group but more research is needed for this section which is so variable and needs more characters to be defined completely. A comparison was also made between the pollen-based cladogram with others based on vegetative and reproductive characters. The sections Tortex and Farinosum were studied based on the pollen morphological characters. Pollen was prepared from preserved flowers, using the critical point drying technique in order to maintain the pollen grain without deformation. Then a) slides were mounted for observations and measurements taken at the Light Microscope and b) photographs were observed and taken at the Scanning Electron Microscope (SEM). 20 species and 17 pollen characters were used that, after coded and polarized (with the outgroup H. wagneriana), were analyzed with the computer program PAUP, generating the respective cladograms. A cluster analysis and Factor Analysis was also performed with the quantitative data using SYSTAT. It was finally determined that there were enough characters to separate and recognize one section from the other, and that there are two main stereotypes: a disc-like shape which corresponds to the tortex section and the bell-like shape which almost acters: a) one based in seeds (Michelle Anderson 1993, intern 1992) and b) with other cladograms more completely (morphological and reproductive characters) by Dr. L. Andersson 1992. Even though both show almost the same groupings, the species position are not so clear. That is the reason that more species are required to see the variations of the characters to make a closest approach based on the pollen characters. At least now it is known which characters are more valuable to study Heliconia pollen: the grain polarity; and the distal and proximal shape, including the germination pore.

This research was supported by a grant from the Smithsonian Women's Committee.