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!