Abstract
Qualitative model-based reasoning techniques have been applied to a wide variety of physical systems. However, one class of physical systems that has received little attention is plant biological systems. These systems are extremely important and appear to be amenable to qualitative modeling. In this paper, we present a prototype qualitative model of photosynthesis in C3 plants. We report on how the structure of the system, and the main processes occurring, can be represented explicitly, and how the behavior of the system can be obtained qualitatively. We also present some results from our initial studies.