Adriana Fung

Comparing leaf heat tolerance within plant species native to southern California

Faculty Mentor: Gretchen North, Biology Department

Major: Biology

Funding: Sustainability Fund Summer Fellowship


Heat is a stressor that has been an increasing issue for plants in Southern California due to the steady increase in temperature due to climate change. Heat stress can cause an array of morphoanatomical, physiological and biochemical changes in plant leaves. These changes can affect the plant’s growth and development, and can ultimately lead to plant death. This study proposes to compare two native woody species in Southern California, Heteromeles arbutifolia (toyon) and Prunus ilicifolia (Hollyleaf cherry). Both are shrubs or small trees in the Rosaceae family, which has many economically important and widely cultivated garden species, including ornamental cherry and pear (Prunus and Pyrus species). Being native to the hot and dry climate of Southern California, these plants have evolved mechanisms to combat various stresses. Prevention of overheating and damage to photosynthesis by photoinhibition can be achieved by certain mechanisms such as chlorophyll fluorescence, thickness of the cuticle of the leaf, and slow rate of leaf water loss. Many studies have been done on both possible differences in heat tolerance between species, but few have investigated differences within species. This study will focus on different leaf types in both species to determine whether immature vs. mature leaves, sun vs. shade leaves, and island vs. chaparral subspecies differ in heat tolerance and how these differences might relate to leaf anatomy and physiology. Results of the study are preliminary, but further research will be done to help develop guidelines for planting and caring for shrubs and trees in Southern California.


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