Abstract Detail

Anatomy and Morphology

Patel, Cailan [1], Morris, Rebecca [2], Cantley, Jason [3], Simonin, Kevin [4].

Effects of saline environments on morphology in Chenopodium oahuense of the Hawaiian archipelago.

The newly described Chenopodium oahuense ssp. ilioensis from the Hawaiian Archipelago is restricted to the world’s tallest seacliffs and adjacent habitats on the Island of Moloka’i. The Moloka‘i seacliffs are exposed to intense winds, salt spray, and strong solar irradiation. Chenopodium oahuense ssp. ilioensis was segregated from the more widespread C. oahuense s.l. due to its prostrate habit, smaller average leaf size, and succulent leaves—all features that may represent adaptations to the taxon’s uniquely harsh environmental habitat. As Chenopodium oahuense ssp. ilioensis is allopatric in distribution from other forms of C. oahuense s.l. across the archipelago, it is unclear if certain morphological features represent evolutionary adaptations to the Moloka‘i seacliffs. Moreover, initial inland greenhouse outplantings away from the direct effects of salt spray resulted in plants with significantly less leaf thickness.  Specifically, to understand the transition between the widespread, large-leaved C. oahuense s.l., and small succulent leaves of the prostrate C. oahuense ssp. ilioensis, this study investigated the role of two environmental pressures in a controlled greenhouse experiment: oceanic salt spray applied to leaves, and oceanic salt water applied to soil. Four experimental treatments were used on plants in a greenhouse for 10 weeks: a control, foliar salt spray, salt water applied to soil, and both salt spray & saltwater applied to soil. Morphological data was collected during two-week intervals including leaf surface area to thickness ratios, epidermal bladder cell (EBC) density, and stomatal density. Initial results suggest a general trend in bladder cell density over 10 weeks of treatment of C. oahuense ssp. ilioensis had, on average, statistically lower densities of epidermal bladder cells on both adaxial and abaxial surfaces, and different surface area to thickness of leaf ratios leaves. Our preliminary results indicate that the small succulent leaves of C. oahuense ssp. ilioensis could have evolutionary adaptations specific to life in a harsh environment as similar responses are known for other lineages. For example, lower densities of EBCs, may be correlated with salt storage inside the smaller and thickened succulent leaves which may effectively produce more photosynthetically efficient leaves that are more osmotically balanced and while simultaneously reducing evapotranspiration. Ongoing studies will process stomatal density as well as additional morphological and physiological data for a more complete understanding. We hope these results will help us better understand the significance of succulent leaves and prostrate habits in the habitat to which it is confined. 

1 - 3045 Santa Maria Drive, Concord, CA, 94518, United States
2 - San Francisco State University, 1600 Holloway Avenue, San Francisco, California, 94132, USA
3 - San Francisco State University, Biology, 1600 Holloway Ave, SF State University Biology Department, Hensill Ha, San Francisco, CA, 94132, United States
4 - San Francisco State University, Department of Biology, 1600 Holloway Avenue, Hensill Hall, San Francisco, CA, 94132, USA


Presentation Type: Poster
Session: P, Anatomy and Morphology Posters
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 5:00 PM Time and date to be determined
Number: PAM004
Abstract ID:779
Candidate for Awards:None

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