Document: MAR-3-35-48

Environmental conditions affect chamise, Adenostoma fasciculatum, leaf structure.

NAROG, M.G.*

USDA Forest Service, Pacific Southwest Research Station, Riverside, CA 92507 USA ¹

Abstract:
Chamise, Adenostoma fasciculatum, is the most common California chaparral shrub. It is well adapted to its unpredictable Mediterranean climate. When found among other chaparral species, it may dominate harsher south facing slopes. Mature chamise typically have simple, ericoid-shaped leaves suitable for survival in a xeric environment. Complex leaf shapes are initially produced on resprouting and seedling chamise and may be a relict morphology retained from the plant's subtropical origins. Flexible leaf morphology may be a survival strategy that permits chamise to increase its growth rate by expanding its leaf surface area and hence photosynthesis. Complex leaves generally are produced for a short period of time and are ultimately replaced by simple ericoid leaves. Leaves of different complexity can be observed on the same plant. However, complex leaves are rarely observed on mature plants. Experiments were conducted to determine if environmental factors and resource availability affect the production or retention of complex leaves. Greenhouse grown chamise were subjected to different shading and hydration levels. Samples from each plant were evaluated and leaf morphology was ranked from simple to complex. Chamise grown under shaded and well-hydrated conditions produced and retained more complex leaves. Plants given more light and less water began producing simple leaves sooner. Flexibility in chamise leaf morphology may be advantageous for survival in an erratic, limited, or competitive environment.

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This abstract is being presented at: 10:30 AM in session:
Poster Session #1: Light Relations.