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 This saguaro was about 25 feet tall and had several arms. Saguaros begin to grow arms when they are 50 to 70 years old. Kyle estimated this saguaro to be 100 years old. The next series of observations I wanted to make was to look at tall cactuses with arms. It seemed that I was able to find more of these older cactuses than younger ones. One of these older saguaros especially interested me. I noticed that its skin was black and dead at the bottom, and toward the top it turned to yellow and then to green. On the arms there was a large nest made out of big twigs. Because of its size, I suspected that it was a hawk's nest. There were five arms protruding from the cactus, and it had lots of holes and cuts in it. The holes I could see in the saguaro were nests, probably made by gila woodpeckers and possibly occupied by desert cactus wrens and elf owls. The saguaro forms a hard lining around those nests, which are called saguaro boots. I could see the outer edges of these brown boots on the surface of the cactus. One particular cut, located in the black area, looked as if someone had taken an axe to it. This saguaro was probably 25 to 30 feet tall and around 100 years old. Because saguaros grow so slowly, it might take 50 to 75 years for them to grow their first arms. Arms are important to them because they store extra water. After 100 years, they usually have several arms. After 200 years they have many arms.  Click to enlarge Finally, I came upon an upright saguaro in which the bottom four feet were dead and black, and the rest of the saguaro was just ribs. What amazed me was how the ribs were bound perfectly together in a circle, stopping anything from coming in. Also, the skin was not even connected to anything anymore, so you could have lifted the skin casing right off the saguaro. On the inside, I noticed that it was filled with a powdery yellow substance. I wondered what that powdery substance was. I thought this must be the dry remains of the flesh of the cactus. After doing a little research, I found out that the powdery substance is like a big sponge when saturated with water and is used to store water to keep the saguaro alive. |
 Click to enlarge I saw many decomposing cactuses lying on the ground with their ribs exposed. After the whole saguaro has decomposed, all that is left are the ribs, which lie on the ground in small piles. I could not believe how many rib piles I found throughout the hills. One group of ribs was still intact and you could easily see the outline of the saguaro. The way that the arm connected to the body was incredible. The arm was connected to two or three of the ribs, and the ribs twisted a little bit at the bottom, making them look like a spiraling staircase. Also, on some of the ribs were round knots with holes in them, like the knots you find on trees. After doing all these observations, I went back and looked through my journal and pictures. I began to realize that most of the cactuses had black dead skin on the bottom. I then found a dying cactus that was completely black and decayed at the bottom. The bottom looked as though it had been eaten away, but the top and a little bit of the side were still somewhat thriving and intact. This cactus had been eaten away so much that it mostly no longer had its form. It also had several cracks and bits of dead skin lying on the ground all around it. At first I began to worry. What if this was a disease and the saguaro cactuses are dying out? I began to come up with some theories. Maybe animals were eating the flesh of the saguaro. Maybe the sun was damaging the saguaros. However, if the sun was damaging them, how come the damage was only at the bottom? Maybe the saguaros all had a disease that was slowly causing decay. I decided to do some research to find out the answers to these puzzling questions. |
