Fouquieria splendens is a large shrub with characteristics typical of both drought deciduous and stem succulent perennials that occurs throughout the desert Southwest. The flood plain within the Philip L. Boyd Deep Canyon Research Center near Palm Desert, California received only 37 mm of rain from September 2006 through June 2007, resulting in an average soil water potential of -118 MPa in the rooting zone of F. splendens, resulting in one of the driest winters ever recorded for the site. The current study examined the ecophysiological response of the plant to the drought, measuring stem and soil water potentials, stomatal conductance and leaf fluorescence for 20 individuals at three elevations.

Results/Conclusions

The average stem water potential, which was not statistically significant between plants with and without leaves, averaged respectively
-1.47, -1.46 and -1.69 MPa at the three elevations. The lowest elevation plants, which were in a floodplain and kept their leaves during the entire year-long course of the study, had an average stomatal conductance of 43.6 mmol/m²/s and average F_v/F_m of .581. Preliminary results support a conclusion that the water relations of Fouquieria splendens are much more like a succulent species than a drought-deciduous species.