Abstract Detail

Developmental and Structural Section

Hodge, John [1], Kellogg, Elizabeth [2].

Patterns of Inflorescence Development within selected members of Andropogon and Schizachyrium.

The tribe Andropogoneae within Poaceae is a clade of economically and ecologically important taxa with a complex evolutionary history due to a rapid radiation event. Ongoing work has shown that two genera Andropogon and Schizachyrium as closely related to one another despite often having distinctive morphological patterns. To better understand the underlying differences and potential similarities in inflorescence morphology within this clade a developmental study was undertaken using three taxa endemic to North America, A. gerardii, A. virginicus, and S. scoparium. Scanning electron microscopy (SEM) was used to capture images of inflorescences of the species across developmental time which were used to infer general patterns. Measurements were also obtained using ImageJ in order to compare to relative developmental trends of various inflorescence and spikelet structures that were not as readily apparent. In all taxa, paired spikelet branches initiate along inflorescence branches in a acropetalous manner followed by basipetalous differentiation. Despite this similarity there are also several traits such as lateral branching and floret differentiation that vary between taxa. S. scoparium lacks lateral branching, whereas both Andropogon produce lateral branches. In addition a strong basipetalous gradient in spikelet length was often observed for S. scoparium. Despite the presence of lateral branches in both species of Andropogon, A. virginicus has several traits that are not present in A. gerardii. The lateral branch(es) of A. virginicus develop at similar rates so that different axes of the inflorescence mirror one another at maturity. Its spikelets are also distinctive; the floret meristems of the pedicellate spikelets abort and the anther number of the sessile spikelets is reduced. Thus A. virginicus spikelets are developmentally distinct from both A. gerardii and S. scoparium. This study overall highlights the inflorescence diversity present just within a single clade of a tribe recognized for being morphologically diverse.

Broader Impacts:

1 - University of Missouri-St. Louis, Department of Biology, One University Blvd., St. Louis, MO, 63121, USA
2 - University of Missouri - St. Louis, Department of Biology, One University Boulevard, St. Louis, MO, 63121-4499, USA, 314/516-6217

Keywords:
Andropogoneae
Poaceae
Andropogon
Schizachyrium
Andropogon gerardii
Andropogon virginicus
Schizachyrium scoparium
Inflorescence development.

Presentation Type: Oral Paper:Papers for Sections
Session: 26
Location: Jasperwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 10:45 AM
Number: 26003
Abstract ID:215
Candidate for Awards:None