Research Training ProgramSmithsonian
Institution
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| David C. Taylor Sam Houston State University Huntspatch, Texas Harold E. Robinson, Ph.D. "This experience has certainly increased my awareness of the importance of natural history collections to systematics research." |
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Restriction of Pepinia (Bromeliaceae: Pitcairnioideae) and taxonomic revisions
ABSTRACT
The large genus Pitcairnia (LeHéritier) of plants in the Pineapple family has traditionally been treated as a monophyletic genus containing a variable number of alliances or subgenera. Lyman Smith recognized two subgenera, Pitcairnia and Pepinia, which were later elevated by Varadarajan and Gilmatin to genera. Other than the addition of new taxa to either genus, Varadarajan and Gilmartin's taxonomy remains the most recently published treatment of the genus Pitcairnia. The separation of Pepinia is essentially based upon a seed character: alate or naked seeds in Pepinia and bicaudate seeds in Pitcairnia. Here, a descriptive investigation of seed form reveals that the character is more complex, yielding a series from the totally corticated seed of P. aphelandriflora (subgenus Pepinia) to the narrowly winged and bicaudate seeds of the typical Pitcairnia. Scanning Electron Microscopy (SEM) is employed to illustrate the gradation. Arrangements of chlorenchyma, adaxial water storage adjacent to vascular bundles as seen in sections of Pitcairnia leaves are considered significant and unlikely to have evolved more than once in the genus. Unstained freehand transections were examined with a compound light microscope. The foliar modifications are found in both genera, indicating that the division based upon seed structure is arbitrary and nonphyletic. The genus Pepinia is reduced back into Pitcairnia, and the subgeneric delineation is no longer used. Forty-four species transferred to Pepinia are placed back into Pitcairnia, and five new combinations and one new name are necessary.
This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates (NSF-REU) in the Biological Sciences grant no. DBI 9531331.