In
an earlier post, I spoke of the adaptations of desert plants that
enable them to thrive in an environment where water is scarce. There, I
mentioned the Yucca plant as one example. Another amazing desert plant
is the Prickly-Pear Cactus, or Opuntia. Composed of flattened pads
covered by spines, prickly-pear produces beautiful yellow or magenta
blooms which seem to announce that they are just as
content with their harsh environment as buttercups are, living in a
lush stream-fed meadow. Plant taxonomists sometimes tell stories about
opening their filing cabinets of pressed plant specimens and finding a
prickly-pear glued to its labeled cardboard in full bloom!
Prickly-pear possesses some amazing adaptations to the scarcity of water and scorching sun so characteristic of the desert. Like all plants, prickly-pear must open its stomates or leaf pores to absorb the atmospheric carbon dioxide necessary for the food-producing process of photosynthesis to occur. However, these same stomates are also the place from which water escapes to the atmosphere during daylight hours. This is not a problem for plants growing in ecosystems containing abundant water. Such moisture loss is compensated for by simply drawing more water up from the soil. But prickly-pear can’t afford to lose such large quantities of water since its desert environment is so perpetually dry. In order to get around this problem, it has developed an alternative means of practicing photosynthesis.
Employing a metabolic pathway called crassulacean acid metabolism (CAM), prickly-pear is able to open its stomates only at night, when the chance for water-loss is at a minimum. By manufacturing an enzyme whose affinity for bonding with carbon dioxide is much greater than that used by non-CAM plants, prickly-pear is able to absorb large quantities of carbon dioxide at night, compensating for the fact that its stomates remain closed in the daytime. However, this causes a potential problem. In non-CAM plants, carbon dioxide is prevented from diffusing back out of the stomates and into the air because it is immediately delivered to the sunlight-driven process of photosynthesis. But in CAM plants, carbon dioxide is gathered only at night when no photosynthesis can occur. In theory then, much of the needed carbon dioxide would be lost back into the atmosphere since there would be nothing in the leaf to hold onto it.
Amazingly, prickly-pear and other CAM plants have been outfitted an ingenious method for dealing with this problem by employing a chemical process which converts the carbon dioxide into several acids. These acids in turn store the CO2 until daytime, when they release it to the sunlight-driven photosynthetic process. In addition, the acid-forming nighttime process is isolated within a structure of the cactus pad separate from the area where photosynthesis occurs. This prevents the two chemical processes from interfering with one another.
These adaptations thus enable prickly-pear to avoid the massive water loss which would result in certain death if its stomates opened during the desiccating daylight hours.
We can, I believe, apply the lesson of the prickly-pear to our own experience of the interior desert. Accordingly, we learn to remove ourselves from the desiccating effects of the afflictive emotions of despair, excessive doubt and self-castigation, which can only harm us in the presence of the bright sunlight of a clear-cut ego-self. It is the clearly defined nature of this self that sets it up for being hurt so readily - over and over again. However, when we begin to let go of this overly-individual ego-self through the practice of meditation and time spent in expansive landscapes, our identity becomes more difficult to discover and pin down. Instead, we find ourselves embraced by the Great Mystery in the obscurity of a nighttime intimacy that occurs when the conceptual mind goes dark. It is then that we can finally feel safe to release ourselves to the Larger Self, the one who is One with the very Source of the Universe. In this way, the desiccating effects of the inner desert become the very goad needed to release us from the intense hurt associated with the solidity and bounded nature of the clear-cut ego-self.
Photo: Prickly-pear cactus pads, Canyonlands National Park, UT; November 30, 2013
Prickly-pear possesses some amazing adaptations to the scarcity of water and scorching sun so characteristic of the desert. Like all plants, prickly-pear must open its stomates or leaf pores to absorb the atmospheric carbon dioxide necessary for the food-producing process of photosynthesis to occur. However, these same stomates are also the place from which water escapes to the atmosphere during daylight hours. This is not a problem for plants growing in ecosystems containing abundant water. Such moisture loss is compensated for by simply drawing more water up from the soil. But prickly-pear can’t afford to lose such large quantities of water since its desert environment is so perpetually dry. In order to get around this problem, it has developed an alternative means of practicing photosynthesis.
Employing a metabolic pathway called crassulacean acid metabolism (CAM), prickly-pear is able to open its stomates only at night, when the chance for water-loss is at a minimum. By manufacturing an enzyme whose affinity for bonding with carbon dioxide is much greater than that used by non-CAM plants, prickly-pear is able to absorb large quantities of carbon dioxide at night, compensating for the fact that its stomates remain closed in the daytime. However, this causes a potential problem. In non-CAM plants, carbon dioxide is prevented from diffusing back out of the stomates and into the air because it is immediately delivered to the sunlight-driven process of photosynthesis. But in CAM plants, carbon dioxide is gathered only at night when no photosynthesis can occur. In theory then, much of the needed carbon dioxide would be lost back into the atmosphere since there would be nothing in the leaf to hold onto it.
Amazingly, prickly-pear and other CAM plants have been outfitted an ingenious method for dealing with this problem by employing a chemical process which converts the carbon dioxide into several acids. These acids in turn store the CO2 until daytime, when they release it to the sunlight-driven photosynthetic process. In addition, the acid-forming nighttime process is isolated within a structure of the cactus pad separate from the area where photosynthesis occurs. This prevents the two chemical processes from interfering with one another.
These adaptations thus enable prickly-pear to avoid the massive water loss which would result in certain death if its stomates opened during the desiccating daylight hours.
We can, I believe, apply the lesson of the prickly-pear to our own experience of the interior desert. Accordingly, we learn to remove ourselves from the desiccating effects of the afflictive emotions of despair, excessive doubt and self-castigation, which can only harm us in the presence of the bright sunlight of a clear-cut ego-self. It is the clearly defined nature of this self that sets it up for being hurt so readily - over and over again. However, when we begin to let go of this overly-individual ego-self through the practice of meditation and time spent in expansive landscapes, our identity becomes more difficult to discover and pin down. Instead, we find ourselves embraced by the Great Mystery in the obscurity of a nighttime intimacy that occurs when the conceptual mind goes dark. It is then that we can finally feel safe to release ourselves to the Larger Self, the one who is One with the very Source of the Universe. In this way, the desiccating effects of the inner desert become the very goad needed to release us from the intense hurt associated with the solidity and bounded nature of the clear-cut ego-self.
Photo: Prickly-pear cactus pads, Canyonlands National Park, UT; November 30, 2013
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