To test the hypothesis that UV filtering in situ would de-harden plants and increase vulnerability to subsequent UV exposure while dry, plants from all three field treatments were subjected to a laboratory UV exposure-recovery assay. An additional 10-15 shoots per sample were randomly selected from the field samples and given a UV-A/B treatment while dry. Samples were placed under four T8 reptile bulbs (ReptiSun 10.0 UVB, Zoo Med Laboratories Inc., San Luis Obispo, CA, USA) in culture dishes covered by UV-transmitting acrylic to filter out UV-C wavelengths, which, in nature, are absorbed by earth’s atmosphere. Lamps were placed 2.5 cm from specimens for a UV-A/B flux rate of 80 mmol m-2 s-1and 160 µmol m-2 s-1 PAR for 14 hours (rotated once during treatment) with a fan to circulate air under the lamp. Temperature and RH were monitored with an iButton data logger (Maxim Integrated, San Jose, CA, USA; 26°C mean temperature, σ = 1.1°C, 19% mean RH, σ = 1.4%). After UV treatment, shoots were prepared for an eight-day chlorophyll fluorescence recovery series as above. To test laboratory UV effects, we compared these laboratory treated samples with their respective field subsets (UV-filtered, transmitted, and site-reference) at each time point (T0.5, T24, and T192) using Wilcoxon signed-rank tests on Fv/Fm and ΦPSII.