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"In late summer 1995, the McDowell Park received a tremendous insult from the "Rio Fire." The Rio Fire blackened 14,000 acres within the park, destroying countless plants and wildlife, including the stately Saguaro Cactus which lives more than 200 years (a 5-armed Saguaro is approximately 200 years old - larger ones even older!) or the Ocotillo, which can live 80 to 100 years. Obviously these species will not be replaced in our lifetimes. However, the vegetation in the park, despite years of drought since 1995, has shown the amazing resilience of the Sonoran Desert. While the effects of the fire are still obvious in places, the desert has shown an amazing (and inspiring) ability to renew itself.

For more, including an amazing aerial photo and photos of the destruction caused by the fire, click on
- from the website for the McDowell Park Association

This desert's power of recovery is nothing short of amazing. We saw photos in the visitors' center of the destruction from the Rio Fire but for someone seeing the park the first time, you'd never know two-thirds of it was a blackened mess thirteen years ago. In fact, when we first visited McDowell Park in 2004 we were completely unaware of the fire, which started from a lightning strike during a dry thunderstorm. Over 500 firefighters from all across the West fought the blaze, which damaged a total of 20,000 acres (some outside the park) in 110-degree July heat. Click on that first link above for photos of the destruction.

I especially like the part quoted above about the desert's "amazing (and inspiring) ability to renew itself." Maybe we can draw an analogy about the resilience of not only nature, but also humans, when disasters strike.


Although we took a ranger-guided hike on the North Trail to learn more about the flora in the park, each day we were on the trails was a sensory learning experience about all the plants around us -- visual, tactile, auditory, olfactory. I'm able to appreciate nature even more when I know the names of some of the plants, their growth habits, what their flowers or fruit looks like, how indigenous peoples used them, how they provide food or shelter to animals, and so on.

Part of the North Trail.   1-17-08

Ranger Emily (photo below) led our hike, which was attended by about seven people one chilly but sunny January morning. She identified various plants, guessed their ages, told us about their unique characteristics, described how the Hohokum Indians used them, and answered all our questions about desert flora. She also pointed out tracks and scat left by bobcats, coyotes, deer, javelinas, and jack rabbits and identified birds we heard or saw during the hike.

In this entry I'll focus on some of the most interesting and common plants at McDowell Mountain Park. I took some of the photos during the nature hike and others while on the network of other trails in the park. Hopefully I'll be able to accurately match the photos with the notes I took during the guided  nature hike. A lot of the trees and shrubs on North Trail are identified with signs, so that helps!

When I've had questions about some of the plants at McDowell that our brochures don't answer I've turned mostly to this website http://www.desertusa.com for information and photos. Fast links to plants and animals are to the left on the home page.



The most ubiquitous, easily-identified plant that is synonymous with the Sonoran Desert is the Saguaro Cactus (the "g" is pronounced like a "w" and the "a's" are soft: sa-WA-ro). I chose the photo at the top of each page in the 2008 journal because of the distinctive armed cacti silhouetted against nearby mountains and blue sky. That photo is from the North Trail. I've got lots of similar photos from other vantage points in McDowell Park.

Saguaro cacti of various ages on the northern part of the Pemberton Trail loop


Saguaros on the ridge along the Scenic Trail

This is an excellent description of the plant from the DesertUSA website above (passages in italics). All photos in this entry are ones I took, except for the flower:

The magnificent Saguaro Cactus, the state flower of Arizona, is composed of a tall, thick, fluted, columnar stem, 18 to 24 inches in diameter, often with several large branches (arms) curving upward in the most distinctive conformation of all Southwestern cacti.

The skin is smooth and waxy, the trunk and stems have stout, 2-inch spines clustered on their ribs. When water is absorbed , the outer pulp of the Saguaro can expand like an accordion, increasing the diameter of the stem and, in this way, can increase its weight by up to a ton.

Close-up of spines on fluted stem, left. The needles help shade the stems
from the hot desert sun. Note the woodpecker holes in the column.
Little Elf Owls sometimes live in holes in the cacti.

The Saguaro often begins life in the shelter of a "nurse" tree or shrub which can provide a shaded, moister habitat for the germination of life. The Saguaro grows very slowly -- perhaps an inch a year -- but to a great height, 15 to 50 feet. The largest plants, with more than 5 arms, are estimated to be 200 years old. An average old Saguaro would have 5 arms and be about 30 feet tall . . .

Relatively "young" Saguaro, left, has nubs that haven't grown into "arms" yet.
The cacti on the right are a little older, but still aren't grand denizens of the desert yet.


"He went that-a-way!"  Unusual arm, on the left, points around instead of up. Although the Saguaro on the right isn't real tall, the large number of "arms" indicate it is quite old.

The slow growth and great capacity of the Saguaro to store water allow it to flower every year, regardless of rainfall. The night-blooming flowers, about 3 inches wide, have many creamy-white petals around a tube about 4 inches long. Like most cactus, the buds appear on the southeastern exposure of stem tips, and flowers may completely encircle stems in a good year.

Arizona's state flower (photo from DesertUSA website above)

When you see the abundance of large, multi-armed Saguaros in McDowell Park, you wonder how they survived the fire. Yes, there are a few distinctive skeletons visible from the trails, but they are scattered randomly throughout the park. Incredible resilience.


Those woody ribs, above, are what gives structure to the tall cacti. They were used to build the old Pemberton ranch house that I mentioned in a recent entry.

I am totally fascinated with Saguaro cacti and in awe of their age and durability, just as I am in awe of centuries-old trees in old-growth forests around the country.

Let's check out some other types of cactus here . . .


In the last entry I mentioned that the preferred food of javelinas is the Prickly Pear Cactus and I surmised that was the reason I saw more of the cacti in urban areas than in the park! This is the equally distinctive flat, round-leaved cactus depicted along freeway interchanges in nearby Scottsdale, AZ. You can see a photo I took in the January 17 entry.

Here are some real ones:

There are about a dozen types of Prickly Pears in the desert Southwest and similar ones seem to grow lots of places in the southern half of this country. Some folks who live out our direction from Roanoke, Virginia even have them in their yards! (They don't look quite right in such an environment, however -- but who asked for my opinion??)

Prickly Pears come in a variety of colors and range in height from about one to six feet tall. Here are two types we saw along the Pemberton Trail in McDowell Mountain Park (above and below). There are two other photos of Prickly Pear clusters along the Pemberton Trail in the January 19 entry.



All Prickly Pears have flat, fleshy pads that resemble thorny leaves. Photosynthesis occurs here. The pads also store water and produce flowers and fruit. Again, none of them were in bloom in January when we visited. Check the DesertUSA web site for photos of the plants with fruit and flowers.


Various types of Yucca can also be found across the USA (lots around Atlanta when I lived there) but they are most prevalent in the desert areas in the western part of the country. I saw a few of the Soaptree variety (I think) in McDowell Park, but not many. This evergreen, palm-like shrub can get up to eighteen feet tall and has clusters of white, bell-shaped flowers along the top of its stalk in the spring. In January, only little bare branches remain on the stalk where the flowers and seed pods used to be:

The Soaptree Yucca derives its name from the soapy material in its roots and trunks which made this plant a popular substitute for soap. Native Americans used the coarse fiber of the leaves for weaving baskets. Cattle enjoy the tender young stalks, and chopped trunks and leaves are still utilized as emergency cattle feed in times of drought.  (from the following web page: http://www.desertusa.com/magfeb98/feb_pap/du_soapyucca.html )

Wikipedia also has some good photos and information about the Soaptree Yucca: http://en.wikipedia.org/wiki/Soaptree_yucca


This is another cactus that is easy to identify. There are several types of Barrel cacti in the southwestern USA and Mexico. The kind we saw at McDowell Park are Sonora Barrel Cactus, which are a pretty reddish purple:

One cactus is down for the count but hasn't decayed yet.


Bright yellow flowers bloom on top of the cactus in the spring.

Emily told us that Barrel Cactus is nicknamed "Compass Cactus" because it tends to lean toward the sun.

For more information about Barrel cacti, see  http://www.desertusa.com/mag99/june/papr/barrelcactus.html


I'll mention this cactus next since the only photo I have of it is with the larger Barrel Cactus that I just talked about:

Ranger Emily identified these as Strawberry Hedgehogs. Apparently they are one of the few cacti from which you can actually get water if you're really desperate. Why really desperate? Because those spines are extremely sharp!! I wouldn't want to have to cut into one.

The flowers are scarlet or fuschia-colored and cup-shaped. This cactus is one of the first to bloom in the spring. See http://www.desertusa.com/mag00/mar/papr/hhog.html.


Another interesting Sonoran cactus species in the Cholla. There are over twenty kinds of Cholla that have adapted to the varying terrain, elevations, and temperatures in the American Southwest. Ranger Emily pointed out several different kinds to us on our nature walk.

My favorite is the Teddy Bear or "Jumping" Cholla, so named because it has clusters of barbed spines called glochids that break off the stems and roll around on the ground like tumbleweeds.

Cody and I found out one day that the little balls are very difficult to remove from the skin and the spines hurt like heck. We were just walking along the road in the campground our second day in the park when he got one stuck to the side of his foot. He was in pain but patiently waited for me a couple of minutes to remove the doggone thing. I was unable to grasp just one tiny spine to pull it off and it really stung each time I touched the sharp ends of the thorny ball. I finally had to step on the thing with my shoe -- and then I had trouble getting it out of the sole!!

Cody learned very fast to stay in the middle of the trails or follow  r-i-g-h-t  b-e-h-i-n-d  u-s  and not go wandering off into the desert!

On our nature walk Emily showed us an old packrat nest. The entrance was cleverly protected by little balls of thorny Cholla to keep predators away. That's a great example of adaptation and symbiosis among the organisms that live in this harsh desert environment.

Despite the "lethal" nature of this plant, I absolutely loved seeing the Teddy Bears along the trails and roads. They are so pretty when they're backlit by the sun. They look soft and fuzzy. As mentioned, they definitely are NOT soft and fuzzy.

Buckhorn and Staghorn Chollas, below, have more slender, segmented stems than Teddy Bear Chollas. They are hard to distinguish from each other. Emily pointed out both kinds during the tour of the North Trail and fortunately some of them had identification signs:

There are numerous Staghorn and Buckhorn Chollas in the park, especially in the North Trail loop area. Emily showed us the fuzzy remains of the edible fruit, which is long gone by January.

We also saw some Christmas Chollas during our nature walk. They are more common in the Chihuahuan Desert farther south.in Arizona, New Mexico, and Texas. I don't have a photo of Christmas Cholla but you can see what they and other types look like here: http://www.desertusa.com/mag99/may/papr/chollas.html



This shrub appears to be in the cactus family but it isn't. Narrow, thorny spindles grow up to twenty feet tall and bear bright red flowers in the spring. After a rain small leaves appear on the canes (branches) but disappear when the plant gets dry again. Ranger Emily, shown with Jim in the photo below, explained that the numerous needles on the branches help to shade the plant to facilitate water retention.

Native tribes like the Hohokam Indians used the leaves, fruit, and flowers for medicinal purposes. You can see other photos of the Ocotillo and its flowers here: http://www.desertusa.com/nov96/du_ocotillo.html


Although this densely-branched green or bluish-green shrub appears to have no leaves, it does have tiny ones. Male and female plants bear cone-like flowers. You can make tea from green or dried branches. Iindigenous peoples have also used the different varieties of the plant for medicinal purposes for centuries. http://www.desertusa.com/april97/du_mormontea.html.



One of the most adaptable and prevalent shrubs in the desert Southwest, the evergreen Creosote Bush grows up to 10-12 feet tall if it has plenty of water -- and even wider than that. It's everywhere in McDowell Park, identified by its waxy, pointed, yellow-green leaves which were used by native peoples to make antiseptics and emetics. The plant reportedly emits a musky odor when rainfall releases volatile chemicals in the leaves but the only time we smelled it was when Emily had us put our noses to the leaves during our nature walk..

The ranger told us there are some Creosote Bushes in California that are 12,000 years old, making them the oldest plants on earth. Amazing. She also showed us the fuzzy seed capsules on the branches and ground around one of the shrubs. This link gives directions for starting new plants from the seeds: http://www.desertusa.com/creoste.html.


I'm sure glad I took some of these photos with the identifying signs because the picture of the Honey Mesquite below looks very similar to the Creosote Bush above -- from a distance. There are three types of Mesquite. This large shrub or small tree is also very common in the deserts of the Southwest, including McDowell Park. Although the yellowish-green leaves are deciduous, this tree was full of long, narrow, pointed leaves in mid-January:

Mesquite is quite a useful plant. I took the interesting information below that is in italics from the DesertUSA page about the plant:

All 3 [varieties of Mesquite] are deciduous and have characteristic bean pods which have long been used by humans, wildlife and livestock as a food source. It is estimated that over 75% of a Coyote's diet in late summer is mesquite beans.

Native Americans relied on the mesquite pod as a dietary staple from which they made tea, syrup and a ground meal called pinole. They also used used the bark for basketry, fabrics and medicine. A favorite of bees and other insects, mesquite flowers produce a fragrant honey.

The taproots, which can be larger than the trunk, are often dug up for firewood. Next to Ironwood, mesquite is the best firewood of the desert, because it burns slowly and is smokeless. The wood is also used for fence posts, tool handles and to create aromatic charcoal for barbecuing.


I had to find another source for additional information about the unique Ironwood tree, which Ranger Emily told us has wood so dense that it sinks in water. There are additional links on the web page regarding the cultural and ecological value of the tree.

Here is a photo of a small Ironwood Tree on our nature hike along the North Trail:

Ironwood grows only in the Sonoran Desert at altitudes below 2,500 feet. Like the human sunbirds who flock to the desert each winter, Ironwood doesn't like to get too cold! This large species, which can reach heights of 45 feet tall, can also live up to 1,500 years. Wow.

Ironwoods have bluish-green compound leaves that are almost fern-like. Purplish or white flowers bloom in the spring, and brown, hairy pods with edible seeds appear in July.

The cool, shaded microclimate in, under, and around Ironwood trees provides an important ecological biodiversity in the hot desert. This quote comes from the Pima County website link above, which has more interesting information about Ironwoods than you'd believe is possible!

"By keeping ancient ironwoods alive, we maintain the oldest medicine show, native wildlife menagerie and migratory pollinator bed-and-breakfast in town. These hardy old trees provide ideal habitat for everything from night-blooming cacti to tree lizards, desert bighorn and cactus owls. The list of residents living under a 45-foot ironwood reads like the Who's Who of the Sonoran Desert."    - Gary Nabhan

Here's my photo (again) of a magnificent old Ironwood on the Pemberton Trail:

The web page goes on to say that more than 230 plant species have been recorded starting their growth within the protective microclimate under Ironwood "nurse plants."  "This also creates an optimum wildflower nursery which is foraged by rabbits, bighorn, and other native species . . . In addition to the birds [150 species], there are 62 reptiles and amphibians, and 64 mammals that use Ironwoods for forage, cover and birthing grounds."

Double wow. That's almost as impressive to me as the ripe old age they can attain.


I learned to distinguish Foothill Paloverde trees by their smooth, yellowish-green green trunks and branches. "Palo verde" is Spanish for "green wood" or "green stick." The Foothill variety (in the photo below) reaches about twenty feet. The other common variety has bluish leaves and stems and gets twice as tall. I didn't notice any of the blue ones at McDowell but there may be some there..

The Foothill Paloverde is another long-lived tree, capable of living up to 400 years. The tree can photosynthesize through its green bark, which is unusual. The tree can drop leaves to combat heat and branches to protect itself in a bad drought. In the spring the tree is briefly covered in masses of yellow flowers. You can see a photo of the flowers and learn more about Paloverdes here: http://www.desertusa.com/mag01/aug/papr/palov.html


My photo of Christmas Cactus didn't turn out well so I just deleted it and didn't even talk about THAT plant above . . . but in the holiday spirit, here's some Desert Mistletoe! I don't know if you can use it to garner kisses like the usual kind of mistletoe hung up at Christmas-time. I suppose you could if you live in the desert Southwest.

I doubt any of us on the nature hike would have noticed the tangled partial-parasite in the Paloverde tree above if Ranger Emily hadn't pointed it out to us. It has pinkish-coral berries during the winter and scented flowers in the spring. http://www.saguaro-juniper.com/i_and_i/trees&shrubs/mistletoe/mistletoe.html


There are many more types of trees and shrubs that have adapted well to life in the Sonoran Desert, including McDowell Mountain Regional Park. I haven't mentioned common ones like Agave, Brittlebush, and Jojoba simply because of lack of space -- and photos! I've included links from three or four good web references in this entry, and you can find many more by doing an internet search.  These sites have additional links to follow for further information, if you're botanically inclined.

The best places at McDowell Park to learn about the flora and fauna are at the visitors' center and the three-mile North Trail, where many of the plants are identified. We didn't do our ranger-guided hike until January 17, four days before leaving the park. Our runs and hikes would have been even more interesting if we'd had more information about the plants from the beginning of our visit.

The winter months are great to run, hike, ride, or camp in the Sonoran Desert, with lots of bright sunshine and pleasant daytime temperatures. We really enjoyed seeing the variety of plants during their dormant season. Spring would be even more interesting, however, when the cacti and wildflowers are in bloom. I hope we can be here sometime to see the show in March and April.

Next entry: we're off to New Mexico tomorrow - come visit the beautiful White Sands area with us! We'll still be in desert terrain but at higher elevations.

Happy trails,

"Runtrails & Company" - Sue Norwood, Jim O'Neil, Cody, and Tater

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2008 Sue Norwood and Jim O'Neil