As we drive into the Tucson area and Saguaro National Park, the questions about saguaros begin to pile up immediately. Questions such as: Why do saguaros grow here? How fast do saguaros grow? How many are there? How big do saguaros get? How come some saguaros have no or a few arms/branches while others have many? How old do saguaros live to be? These and many other questions stimulate our curiosity and wanting us to learn more. I’ll try to answer some of these questions as I take you on a tour of a park dedicated to these magnificent, stately cacti.
Let’s start with a little history and information about this National Park. The park consists of about 92,000 acres in two units, the Saguaro West Tucson Mountain District (TMD) is about 10 miles west of Tucson while Saguaro East Rincon Mountain District (RMD) is about 10 miles east of Tucson. Physically, they are located about 30 miles apart but driving time is estimated to be 50-60 minutes due to city traffic. Saguaro was designated a National Monument in 1933, was added to in 1961, and promoted to a National Park in 1994. Both units have very well done Visitor Centers that offer history, cultural and nature exhibits, a video as well as a gift shop. Between the two units, there are 150 miles of hiking trails plus sightseeing roads to get up close and personal with the cacti.
The earliest residents in the area, the Hohokam peoples, settled here in about 200 AD and stayed until around 1450. They were succeeded by other related cultures until Spanish explorers arrived in the mid 1500’s. After the Homestead Act was passed in 1862, much of the area was taken over by ranchers and miners. In the 1920’s, efforts by the nearby University of Arizona and local politicians advocated for the preservation of the saguaro by establishing a park and game preserve.
The saguaro is the largest cactus in the US and is considered a symbol of the American West. Some of us remember the western movies and tv shows from our youth that included saguaro cacti, maybe because a lot of those movies and shows were filmed on the set of Old Tucson located near the west unit of the National Park. Saguaro’s are only found in the Sonoran Desert located in southwest Arizona, extreme southeast California and western Mexico. So how big does a saguaro grow? There are reports that a few reach the height of over 50 feet while the average height is in the range of 25-30 feet. They can live up to 150 years with a few living as long as 200 years. They have root systems that can extend up to a 50 foot radius from the main plant, they do grow in a desert so as they grow they need more roots surface to gather moisture for survival.
The main questions about saguaros arise in regards branching or growing arms. From our discussions with the park rangers, there are theories but not many definitive answers about branching. Branches, or in lay person terms arms, don’t begin growing until the plant is about 15 feet tall or about 75 years old. You might ask, how many arms does a saguaro grow? There are some plants that don’t grow any branches while a few grow up to 40 or 50. That’s a lot of arms! And a lot of extra weight to uphold. Most saguaros have 10-20 branches. So what do those branches do? Well they allow the plant to produce more fruit and seeds, the more seeds the more likely that a few of those seeds will germinate and grow to maturity to perpetuate the species. Those arms also hold moisture that can be used during periods of drought. Below are a couple of fine specimens with lots of arms that we saw during our tour of the Park.
On our travels through the Park, we noticed some plants had branches that were growing downwards. This is likely due to cold, freezing temperatures so the cells in the arm is damaged and loses its rigidity. Sometimes they continue to live and at other times they drop off.
Sometimes there are constrictions in the trunks of the saguaros, this is likely due to frost damage or extreme drought. This may slow down growth but once beyond the point of injury, it will continue to grow normally. Many or most of the saguaros have holes that are homes to birds such as woodpeckers and flickers. Note the hole in the trunk of the saguaro pictured below. Plus these saguaros look like they are flexing their muscles?!! And look at those mighty biceps!
The final question we had is what causes saguaros to die off? Certainly, old age is one cause, we did see a number of cacti that had fallen and the dead horizontal trunk looked very much like the trunk of a tree that fell in a wooded forest. That’s how strong the trunks are. Others die from being trampled by large animals and cattle while some are eaten by rabbits, mice and other small critters. The sharp spikes don’t seem to bother them.
During our visit to both units of the Park, we drove the scenic drives and stopped many times to admire the “forests” of saguaros. Here’s a sample of what we saw on our drives.
Not only are there saguaros in Saguaro National Park, there are other cactus species to observe and watch out for!
Well I hope some questions about saguaro cacti are answered in this post. Like all national parks, we enjoyed our visits to both the east and west units of Saguaro National Park. We also appreciate the efforts to preserve the saguaro habitat for future generations to learn from and enjoy. Here’s a parting photography of the majestic saguaro cacti.
Next up, the Arizona-Sonora Desert Museum.
Until next week, travel safe.