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Abstract Detail

Pteridological Section/AFS

Pittermann, Jarmila [1], Baer, Alex [1], BECK, JAMES [2], Windham, Michael D [3].

Desert dispatch:  water relations of select cheilanthoid ferns (Pteridaceae) native to the southwestern United States.

Pteridaceae are one of the largest and most diverse fern families, occupying a wide range of habitats spanning terrestrial to epiphytic and aquatic to arid niches.  Within the family, members of the cheilanthoid clade stand out by virtue of their successful colonization of xeric habitats. Genera such as PellaeaNotholaena, Bommeria, Pentagramma, and Myriopteris are commonly found in the desert regions of North America and Mexico, where high light and low water availability create substantial ecological challenges.  In an attempt to better understand the suite of adaptive traits that allow ferns to thrive under these conditions, we examined the habitat characteristics and physiological performance of six cheilanthoid species during the late summer monsoon season in southern Arizona. Even in the face of mid-day light levels approaching full sun and leaf temperatures exceeding 30°C, we found that leaf water potential rarely dropped below -2 MPa, while stomatal conductance in several taxa reached values in excess of 1000 mmol/m2/s.  We hypothesize that xeric-adapted cheilanthoid ferns are physiological opportunists with diverse morphological and physiological strategies for surviving diurnal and seasonal drought.  These strategies allow them to tolerate or compensate for abiotically stressful conditions in the short term by sustaining regular mid-day periods of high evaporative demand. Monsoon precipitation combined with roots that extend deep into rock crevices seem to provide sufficient water access to maintain leaf hydration during this critical time.  Our data provide some evidence that physiological adaptability may partially explain the ecological specialization of cheilanthoid ferns and, perhaps, Pteridaceae as a whole.

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1 - University of California, Ecology and Evolutionary Biology, 1156 High Street, Santa Cruz, CA, 95064, UsA
2 - Wichita State University, Biology, 1845 Fairmount, Box 26, Wichita, KS, 67260-0026, USA
3 - Duke University, Department of Biology, Box 90338, Durham, NC, 27708, USA

Primary xylem
water potential.

Presentation Type: Oral Paper:Papers for Sections
Session: 7
Location: Pines North/Boise Centre
Date: Monday, July 28th, 2014
Time: 9:00 AM
Number: 7003
Abstract ID:636
Candidate for Awards:None

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