Nurse Plants
For the second weekend in a row we took a morning and went on a family outing. Last weekend we drove out to the desert museum, and this weekend we visited Tohono Chul park. Both of these sites feature desert vegetation and wildlife, which everyone is enjoying learning about.
One of the interesting things we learned is that the saguaro cactus requires a "nurse plant," typically a mesquite tree or a palo verde bush (remarkable for their green photosynthesizing bark), to provide shade when it is young. Thus, when you see young saguaro, they are very commonly growing up into the bows of a low desert tree. After about 50 years, they grow up through the tree, and eventually the tree dies--some theorize because the cactus broad surface root system steals the trees water, but others believe that the relatively short lived desert trees just reach the end of their natural lifespan (about 70 years) and die of old age.
One of the interesting things we learned is that the saguaro cactus requires a "nurse plant," typically a mesquite tree or a palo verde bush (remarkable for their green photosynthesizing bark), to provide shade when it is young. Thus, when you see young saguaro, they are very commonly growing up into the bows of a low desert tree. After about 50 years, they grow up through the tree, and eventually the tree dies--some theorize because the cactus broad surface root system steals the trees water, but others believe that the relatively short lived desert trees just reach the end of their natural lifespan (about 70 years) and die of old age.
