Abstract Detail

Anatomy and Morphology

Klahs, Phillip [1], Clark, Lynn [2].

Grass Spikelet Evolution: Morphology Shaped by Wind.

The wind pollinated spikelets of the grass family (Poaceae) are architecturally beautiful.  These intricate reproductive structures are successful at anemophily despite the remarkable variability in morphology and differences in habitat due to the global distribution of the family. We studied the evolution of grass spikelets by creating ancestral state reconstructions for a series of vegetative and reproductive characters on a plastome phylogeny. Preliminary results show the lengths of glumes and lemmas relative to the entire spikelet evolve independently. Nonrandom patterns were found in the contribution to spikelet morphology from glumes, which may be miniscule or represent the entire length of the spikelet. To further investigate shape evolution in spikelets we created virtual 3D models of spikelets from a limited set of species representing forest, edge, and open habitats to quantify the aerodynamics of grass anemophily in different habitats using computational fluid dynamic simulations. Spikelets were subjected to wind flow from multiple directions and various wind speeds to determine orientations resulting in the highest probability of stigmas encountering pollen. Wind speed and air pressure data from regions of the fluid flow field occupied by the stigmas were compared among the taxa studied. Preliminary results indicate differences between congeners from forest or open habitats, with forest taxa generating larger areas of higher wind speed where the stigmas are positioned.

1 - Iowa State University, 251 Bessey Hall, 2200 Osborn Drive, Ames, Iowa, 50011-4009, USA
2 - Iowa State University, Department Of Ecology, Evolution, And Organismal Biology, 251 Bessey Hall, 2200 Osborn Dr., Ames, IA, 50011, United States

3D modeling.

Presentation Type: Oral Paper
Number: 0009
Abstract ID:159
Candidate for Awards:Maynard F. Moseley Award

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