Grant, Marissa C. , Coons, Janice M. , Carlsward, Barbara S. , Coutant, Nancy E. , Owen, Henry R. .
Structural and Physiological Adaptations of Physaria ludoviciana (silvery bladderpod; Brassicaceae) to Sand Prairie Conditions.
Physaria ludoviciana (Nuttal) OKane & Al-Shehbaz is an endangered species in Illinois and Minnesota sand prairies but occurs commonly in western states. Areas with P. ludoviciana have full sunlight, high summer temperatures, and soils with low water holding capacity. This adverse environment, where few other species compete, creates an ideal niche for P. ludoviciana. Our focus was to investigate structural and physiological adaptations of P. ludoviciana for this environment as well as possible impacts of competing species on P. ludoviciana. Plant material was collected in Mason County, Illinois at the Henry Allan Gleason Nature Preserve. Structural and physiological features of leaves, stems and roots were described. Competition for light was evaluated by planting seeds in growth chambers at either 585 or 175 Â”mol/m2/sec (16h light/8h dark) at 25ÂșC for 4 weeks while measuring growth. Root competition was evaluated by growing vegetative rosettes in 5 different pot sizes with various widths (4-23 cm) and depths (20-36 cm) for 5 weeks while evaluating vegetative parameters. Physaria ludoviciana has several structural adaptations for sand prairie conditions including numerous stomates and trichomes on leaves. However, leaves exhibit C3 anatomy which also is supported by isotope analysis. In transverse section, leaves possess palisade layers on both surfaces with no evidence of water storage tissues. A long taproot and large root:shoot ratio are present as well as evidence of transpirational cooling. Water potentials range from -1.2 to -1.7 MPa. Plants at higher light intensity had significantly greater leaf areas, fresh and dry masses, leaf numbers and root branching than at lower light intensity. Leaf number, area, and mass were significantly greater for plants in larger pots than in smaller pots, suggesting that physical constraints or root competition may limit growth. Understanding adaptations of P. ludoviciana aids our management of sand prairie species.
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1 - Eastern Illinois University, Department of Biological Sciences, 600 Lincoln Ave, Charleston, Illinois, 61920-3099, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Alpine B/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 9:15 AM