Beavertail on the Colorado

Opuntia basilaris

The rocky, almost barren desert of the lower Colorado River valley comes alive in March after winter rains and warm temperatures.  Yellow creosote bush blooms, brittlebush and yellow cups, and purple phacelia shout that spring has arrived.  But, nothing prepared me for the explosion of color that was the blooming of the beavertail prickly pear cactus.  Our annual trip to the river was just a week later this year than usual, and what a difference it made.  Normally I'm happy to see ten or so of these bright pink beauties.  Imagine my surprise and joy to be met with hundreds of the humble little cactus sporting big, bold flowers, everywhere the eye could see.

The flat, jointed pads of the beavertail give rise to its name.  A low-growing prickly pear with gray-green stems and no large spines, the pads are covered with tiny brown bristles called glochids.  These are far more irritating and bothersome to the human body than the big spines.  Note to admirers of the flowers, don't get too close to the plant!

Growing on the rockiest slopes, these plants seem to need little in the way of soil or water.  The flowers range in color from bold magenta to delicate pink, and I understand, there are even yellow and white varieties.  In this section of the Sonoran Desert along the Colorado River, I saw none of the yellow or white.

The flowers are followed by fruits, magenta to pale green, maturing to dry brown-gray, barrel shaped and usually spineless. Cactus bees are the pollinators.

A drive along Cienega Springs Road, and later a hike up Buckskin Trail literally took my breath away with the stunning glory of these flowers. The Death Valley superbloom had nothing on this display!

Prickly Pear

Prickly Pear

Opuntia sp.

The cactus are bursting into bloom, at the Desert Museum we're doing Wildflower Walks and Cactus Tours, so what better time to think about the Prickly Pears. In the family Cactaceae and the genus Opuntia, prickly pears are native only to the Americas, but are now seen growing around the world, and are even considered invasive pests in many places.   It's easy to get confused about what cactus are included in this genus as taxonomy is ever-changing.  Chollas were traditionally included with prickly pear in the Opuntia genus, but have now been separated into their own genus - Cylindropuntia.  Most sources now agree that now Opuntias only include the paddle cactus or, as we know them, prickly pears.  There are approximately 200-300 species included in the genus, only a small portion of which are native to  North America. 

Prickly pears are typically easy to recognize with their flat, rounded stems (also called cladodes) that are protected with two types of spines - large, smooth, fixed spines and tiny, hairlike, barbed prickles called glochids.  The latter easily detach from the plant and penetrate the skin, causing annoying itch and irritation.  Some species are considered spineless, including beavertail and Santa Rita, but all have glochids. 

Santa Rita pads showing glochids

The fleshy pads are actually modified branches or stems that serve several functions - water storage, photosynthesis and flower production.  The flower buds arise from aereoles, and the prickly pear flowers are easily recognizable as those of a cactus as they have many tepals that intergrade with each other; many stamens and a multilobed stigma.   Yellow is the primary color of our native prickly pear flowers.  On some species, the yellow flowers will turn a peachy color by the afternoon before closing.

The main pollinators of our prickly pears are cactus bees - several native bee species that specialize in cactus.  Cactus pollen is gathered and then packed into the bees' burrows to feed the grubs.  Once pollinated, the prickly pears produce elongated, swollen fruit that are juicy and sweet.  Large numbers of the fruit are produced in July and August, ripening to a deep red color.  They are enjoyed by a wide variety of animals including rabbits, packrats, javelina, deer, squirrels, desert tortoises, cactus beetles and many bird species, all of whom help propagate the plants by disbursing the seeds.  People, too, love the fruit!  Also called "tunas" the fruit are sold in many forms such as jelly, candies and lemonade.  The most popular source for tunas , as well as nopales (the young pads) is the Mexican species of prickly pear - Indian Fig (Opuntia ficus indica).  

Engelmann's Prickly Pear Fruit

In North America, prickly pear cactus are found in all the deserts of the Southwest, with different species having adapted to specific locales and elevation ranges.  Most can be found in course, well-drained soil in dry, rocky flats or slopes.  But some prefer mountain piñon/juniper forests and yet others require steep, rocky slopes in mountain foothills.  The little cochineal bug played a major role in the spread of prickly pear to other continents - a fascinating story that I'll save for another day.  Another player in the globalization of prickly pear was the desire of gardeners and plant fanciers to grow exotic species.  Australia, in particular, has suffered from the indiscriminate introduction of prickly pear from South America.  There it has become a terrible, invasive weed whose clonal spread has been difficult to control. 

In recent years there has been medicinal interest in the role that the pectin in prickly pear pulp can play in reducing levels of 'bad' cholesterol while not affecting 'good' cholesterol levels.  The fibrous pectin in the fruit may also lower diabetics' need for insulin.  Both fruit and pulp are rich in slowly absorbed soluble fibers that may help keep blood sugar stable. 

The color of the stems of our native prickly pears varies from the green of Engelmann's to the purple of Santa Rita.  The purple will be more intense in the cool, dry winter months, and a softer blue-gray in the summer once the rains arrive. 

Santa Rita Prickly Pear

Now is a great time to go exploring on the grounds for all the interesting varieties of prickly pear in the ASDM collection. 

And, thanks to the good suggestion by fellow blogger, Marilyn Kirkus, here is a link to an excellent article on harvesting and preparing prickly pear fruit and pads.  Enjoy!

A Color Burst

It was a lazy Saturday morning and I was in sloth mode.  I hadn't even taken my usual walk around the 3-mile neighborhood loop.  If you've ever seen the sloths of Central America, you know that their favorite 'activity' is just hanging out, usually sleeping.  To quote National Geographic, "The sloth is the world's slowest mammal, so sedentary that algae grows on its furry coat."  Rather than in a tree, I had perched myself in a comfy chair on the patio to enjoy the glorious, but all-too-brief show of the trichocereus cactus blooms in the garden.  Big puffy clouds kept the sun at bay and the temperature in the quite pleasant range. 

 

Trichocereus, also known as hybrid torch cacti, are popular with gardeners in Tucson for their huge, brilliant blooms.  Hybridized from tropical species, they are fairly cold tolerant, asking only for a bit of filtered shade and an occasional splash of water.  I have a collection of perhaps twenty plants in my Jardín Cactita, the little cactus garden.  A paltry number compared to the Desert Museum's large collection.

 

 



 

Cactus bees come to gather the abundant pollen and nectar, and pollinated plants will produce large, round fruits filled with tiny seeds. Being hybrids, it's doubtful that the seeds are viable, but I should ask a knowledgeable grower about this.  I might try growing some new plants from seed.

 

 

 For the most part, the blossoms only last one day, closing up by late afternoon, never to open again.  A couple of the species, however, produce flowers that will open for a second day.  Thus, it's important to take advantage of the event, drop what you had planned and simply enjoy!

 

 



 

 

 

 

 

Flower anatomy is primarily what determines the taxonomy of plants.  While it might seem obvious from looking at a plant that it is a cactus, that's not necessarily so.  Many non-cactus plants, for example, have spiny, sharp projections.  People often mistake some euphorbias, agaves and ocotillos for cactus.  Cactus flowers have a multi-lobed stigma (the white, or cream, structure in the center of the photos, the female part) and many stamens (the male, pollen-carrying structures deeper in the center). 

So, I was sipping my coffee, taking photos, enjoying the flowers and watching the hummingbirds zip around.  My year-around hummers are Costa's and Anna's and I am so accustomed to the sounds they make. 

 

 

So, when a new sound entered my consciousness, I looked quickly around to see one of the Anna's being chased by .  .  . a rufous??  Wow, what a surprise!  There was no doubt - the lovely rust-colored wings, the orange-red iridescent throat, and that famous rufous aggressiveness.  Even with my camera in my hand, I was too dumbstruck to take a photo.  Not that he would have slowed down long enough anyway.  The birding experts say the male rufous migrate early, but THIS early?  Oh, that was exciting.  The rufous made a couple more speedy passes by the feeder but never stopped to drink.

 

No sooner had I calmed down than another hummingbird flew right by my face and it was a blur of color that only registered as blue.  Blue?  Sure enough, a few moments later a better view revealed the red beak and the brilliant colors of a male broad-billed.  What a crazy day!  Flying flowers competing with the torches. 

 

A desert spiny lizard came out and posed with the flowers. 



Some Gambel's quail stopped by the snack bar.

 

 

And those flowers just kept on blooming.

 



Maybe every day should be a sloth day!  I won't get nervous until I start to see the algae grow.

The Yellow Moment

There comes a day in April in Tucson when you look around and the entire world is YELLOW; very, very yellow.  And such it is at this moment in time.

It's as though a giant artist has dipped her brush in a big pot of yellow paint and swiped it across the landscape, as far as the eye can see.  For a few glorious days, up to two weeks, the desert will be awash in color.  And then it will be gone, seemingly as quickly as it arrived.  The moment will have passed.  Just as the setting sun paints the mountains in shades of pink and purple in "the pink moment" and then fades away, so too will these colors be gone and slip into our memory.

Palo verdes are by far the most dominant tree in the Arizona upland, and it is the annual bloom of this tree which colors our world.  Several species of palo verde can be found growing around Tucson, including the Foothill (Parkinsonia microphylla), Blue (Parkinsonia florida), Mexican (Parkinsonia aculeata) and several hybrids.   Like most of the Sonoran desert trees north of the Mexican border, palo verdes are legumes, in the family Fabaceae.  Most of you are familiar with legumes due to their common and widespread use for food (think peas and beans).  It's a huge family of 16,000 species, many of which are found in the arid tropics.

Foothill Palo Verde, agave stalk and white-winged dove.

Those of you who know Spanish can figure out that palo verde means 'green stick'.  Sure enough, if you look at the bark, you will see that it is green.  This is a wonderful adaptation to drought.  The tiny leaves fall off during times of drought, so the green bark allows the tree to photosynthesize without the leaves.

But it's the flowers, blooming in such profusion that they completely hide the leaves and branches, which are our focus today.  Flowers in the subfamily Caesalpinia have five separate petals, one of which, the 'banner' petal, is always a little different than the others.  It may be larger, or a different color.  Another characteristic is the 10 separate stamens.  The first to bloom are the Blue PV's, with their deep yellow hue.  All the petals are yellow, but the banner petal is slightly larger and has tiny orange dots.

Blue Palo Verde 

Just as the flowers of the blue palo verde are fading and falling to the ground, the foothill palo verde begins its bloom.  In the areas where the bloom overlaps, it is easy to distinguish the two.  The flowers are much paler yellow in the Foothill PV.  Four of the petals are pale yellow and the banner petal is white.

Closeup of the Foothill Palo Verde flower

More drought resistant than its cousin, the Blue, the foothill grows happily on rocky hillsides, whereas the Blue is more at home in washes where it might receive more regular water.  Foothill can also long outlive the blue.  The flowers of the palo verdes are pollinated by solitary bees.  All species of palo verde produce bean pods following the bloom, which are nutritious and delicious to many animals.

Although palo verdes provide the BIG yellow, many smaller desert plants are also now in bloom and they add their shade of yellow to the sunshiny scene.

Engelmann's Prickly Pear Cactus

Santa Rita Prickly Pear Cactus

Cholla Cactus

Prickly Pear Cactus

Agave Flower

Octopus Agave bloom

Cooper's Paper Flower

Desert Marigold

See what I mean?  Yellow.  Lots and lots of yellow.  Do you think I'm tired of it?  Not a chance.
I leave you with a shot of my back yard and the view toward the Catalinas.  And now I'm going to go out and enjoy it some more!

Of Hedgehogs, Mammilarias, Chollas and Prickly Pears

The cactus flowering season in the desert is in full swing.  Sometimes the beauty you most appreciate is the kind you have to look for, making you work a bit for a delicious reward.  Flowers in the desert can be like that.  To just look out across the landscape, you might see nothing special.  But this land takes you in its hold slowly but surely.  Take the time to wander through it, to really see the many fascinating small sights and you will be surprised and amazed.  Take the strawberry hedgehog cactus, for example.  A rather innocuous, small clumping columnar cactus that is easily overlooked until one day its bright magenta flowers open and Wow!  They seem to be everywhere!  The color is so vivid against the usual desert colors.

Strawberry Hedgehog (Echinocereus engelmannii)

Another species, with lighter pink flowers grows somewhat taller.

The hedgehogs are among the earliest-blooming cactus in our area.  But there's also the lovely Claret Cup which is often the very first to show its stunning finery.

Claret Cup Cactus (Echinocereus triglochidiatus)

Look closely at cactus flowers and you will see what defines the cactus family - many stamen and a multi-lobed stigma.  Many species of prickly pear cactus (Opuntia) inhabit the Sonoran Desert and at our elevation very few of them have begun blooming.  The beavertail (Opuntia basilaris) is native to the lower elevations of the Sonoran Desert and to the Mojave.  It's bright pink blossoms are often open in February and March.  In my yard and around town I see the multi-colored flowers of the long-spined prickly pear now beginning their show.

Long-Spined Prickly Pear (Opuntia macrocentra)

Other native prickly pear species, such as Engelmann's and Santa Rita, will begin blooming sometime this month.  Elsewhere, the giant saguaros, too are getting ready for their show.  In my neighborhood we are fortunate to have a very rare crested saguaro whose bloom cycle is somewhat off-kilter from its cousins'.

Crested Saguaro in Bloom (Carnegiea gigantea)

Already, this specimen is in full bloom and will actually have another bloom period in November.  That I cannot explain!  The 'normal' saguaros are now forming buds and a very few of them have actually opened.  Most, however, will be later this month and into May.

Cholla, the jointed cactus, of which we have a number of species, is also just beginning to show flowers.  A little later, they will be putting on a breathtaking performance in a whole palette of colors.  So far this spring, I've only seen two plants with open flowers.

Many species of cactus which grow in the Mexican portion of the Sonoran Desert are represented at the Desert Museum.  Here are two I saw in bloom last Friday.

Cardón (Pachycereus pringlei)

The cardón is a relative of the saguaro, but grows taller and its branching will occur closer to the ground.  Below is an interesting specimen from the convergent evolution garden at the Museum.

Astrophytum myriostigma

I just have one more genus of cactus to tell you about - Mammilaria. Generally these are tiny, clumping cactus whose flowers from a ring near the crown.  My wild mammilarias are not yet in bloom, but here is a beautiful specimen from the Desert Museum.

And one from my yard whose flowers are not yet open in the early morning when I took this photo.

This small sampling indicates the amazing variety and beauty of the cactus family.  I leave you with the outrageous blooms of the Torch Cactus (Trichocereus) which is cultivated, but not native, in our area.  Mine are just now forming buds, but at the Desert Museum last week we were treated to this stunning display.

Cactus are native only to the Americas, but some bear a striking resemblance to certain euphorbias from Africa, the result of a process known as convergent evolution, and thus defined:  In evolutionary biology, convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.


Here's wishing you beautiful blooms this Spring!