Bobich, Edward , Roth, Allison , Brandy, Ulrich .
Fouquieria splendens (Fouquieriaceae) Produces Leaves and Inflorescences in the Absence of Significant Rainfall in the Sonoran Desert.
Fouquieria splendens (ocotillo) is a large drought-deciduous shrub that usually produces new organs, particularly leaves, soon after summer rains or once temperatures are favorable for production after the usually reliable winter rains in the Sonoran Desert. From September 2006 through February 2007, the flood plain within the Philip L. Boyd Deep Canyon Research Center near Palm Desert, California received only 7 mm of rain, resulting in an average soil water potential of -118 MPa in the rooting zone of F. splendens. For these soil conditions, 54% of the F. splendens surveyed produced leaves, which had an average stomatal conductance of 42 mmol m-2 s-1 on the abaxial side of the leaf, and 84% produced inflorescences. Stem water potential, which did not differ between plants that produced leaves and those that did not produce leaves, averaged -1.3 MPa. There was no correlation between leaf production and plant height; however, flowering occurred for 97% of plants greater than 2 m tall and for only 30% of plants under 2 m tall. Differences in flower production with plant height may be due to the fact that larger plants have greater stored resources to support flower production or that the primary pollinators of ocotillos are hummingbirds, which are present in the late winter/early spring and would be better able to locate flowers on taller plants with more numerous inflorescences. Overall, flower and leaf production and the associated water loss due to transpiration were probably made possible by the relatively high stem water potentials and stored carbohydrates in the stems. It is hypothesized that leaf production may have been cued by one or more of the following: unseasonably warm temperatures, an attempt to recoup carbon lost to inflorescence production, or a stress response resulting from the decade-long drought at the site.
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1 - California State Polytechnic University, Pomona, Biological Sciences, 3801 W. Temple Ave, Pomona, California, 91768, USA
Presentation Type: Poster:Posters for Topics
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM