Cacti Part 2 ~ Prickly Pears

The Opuntiodeae

Not so very long ago, all cacti were just that – cacti. Sure, there were various tribes, but still, all was one big family. Alas, this is no longer the case. Those uppity Opuntia’s have gone and gotten themselves elevated to the status of “subfamily.” Admittedly it’s a big subfamily – around 180 species – and like any family, its members are varied and diverse. Opuntias are distributed world wide, some naturally, but many were helped by humans who carried them (at least the Prickly Pears) everywhere they went. Prickly Pears have been cultivated for centuries as both the pads and the fruits are edible and nutritious.

It’s easy to tell if a cactus is an Opountiodeae. Opuntias grow a unique type of spine, called a “glochid.” Glochids are very small and numerous, usually straw-colored, and they surround the larger spines on the surface of the areole.

The glochids in this picture are huge relative to glochids in other members of sub-family. The following picture shows a plant with average-size glochids.

Glochids are equipped with microscopic barbs. They easily penetrate the skin, but because of the barbs, they are almost impossible to remove completely. They are intensely irritating.

All the Opountiodeae in this area of the Chihuahuan Desert produce yellow flowers, though the tepals of some may tend towards orange or pink. The flower buds are ovoid in shape, and otherwise look like other stems of the plant. The stems surfaces range from smooth to low tuberculate. Here in the south counties, they are all glaborous.

Three genera make up the Opountiodeae.

Opuntia

The word Opuntia was formerly used for all the Opuntias. Now, Opuntias are the plants we  know as Prickly Pears. The taxonomy of the Opountiodeae is not well understood, so for this discussion I am dividing them into two groups – green ones and purple ones.

The green Prickly Pears are simply that – green – always. Three of the green Prickly Pears are common in this area: Camanchica, Englemann’s, and Rufida. In some areas there may be O. Dulcis as well.

Engleman’s Prickly Pear

Englemann’s Prickly Pear is widely distributed throughout the state of Texas, and surrounding states. In size and growth habit it is extremely variable, but the bird’s foot spines distinguish it from other species, at least a little. Englemann’s Prickly Pear can grow quite large in good conditions. As such, it is the largest Opuntia species in the Trans Pecos. The flowers are all-yellow unlike the Comanchica Prickly Pear which has red centers.

Comanche Prickly Pear

This cactus resides only in the hottest parts of the desert along the Rio Grande. It’s most distinguishing feature is the fact that its fruits have few or no spines near the apex. Also, they remain succulent long after ripening.

Comanche Prickly Pears are usually no more than a foot or so in height, but they can grow to 4½ feet in good conditions. The pads are usually broadly obovate to almost circular. They usually have spines on the distal third of the pad with 3 to 7 spines per areole but that is not a reliable way of identifying them as their spination varies significantly. The flowers are yellow with red centers.

O. Camanchica is an attractive cactus when in bloom as this photo taken by Richard Reynolds shows.

Blind Eye Prickly Pear

This cactus (Opuntia rufida) is living at the extreme northern edge of its range and it is not known to live anywhere outside of the Big Bend Region. It is easy to identify as it has no spines at all – only glochids … but it has them in abundance. These glochids are only loosely attached to the plant, and can be dislodged by wind. The plant gets its popular name “Blind Eye” Prickly Pear from these loosely attached glochids. Airborne glochids can blind cattle.

Blind Eye Prickly Pears are particularly showy when blooming as they usually sport two different colored flowers in the spring. Some of the flowers are all yellow. Others are a beautiful peach color.

Purple Prickly Pears

The Purple Prickly Pears present us with a problem. For one thing, their taxonomy is not clearly understood at all, so botanists are forever switching them around as new information about their relations becomes available. This is just a fancy way of saying that you never know what one of these plants will be named tomorrow. Difficult…

In the past we simply called them “Purple Prickly Pears” and if they weren’t all that purple, we called them “Purple-Tinged Prickly Pear.” Now these groups have been further subdivided but the distinctions are not very clear in the wild, and what with the plant’s tendency to hybridize with other close relatives, accurate identification becomes problematic, so for the Purple Prickly Pears we will stick to common, popular names.

More difficulties arise from the fact that all the Purple Prickly Pears are extremely variable. The same species (or what is believed to be the same species), can sport gigantic spines, or practically none at all. They may be blue all over, or blue with purple edges and areoles, or purple all over, or even red. The pigment responsible for the color is commonly used by all the Prickly Pears, and other cacti as well, as a protection against severe dehydration, excessive sun, extreme cold, or simply on the whim of the plant, so you can’t rely on a purple prickly pear actually being a true Purple Prickly Pear.

The most noticeable Purple Prickly Pear is Opuntia macrocentra although even this one has been split out and placed in the diplopurperia group. This plant is usually simply called the Purple Prickly Pear. The pads are more red than purple, even when growing conditions are ideal. Because of its color, this plant is easily spotted at a distance.

In bloom, it produces striking yellow blossoms with red centers. The fruits are smaller than most other species, but they are also sweeter.

The less distinctive Purple Prickly Pear is the “Purple Tinged” or “Purplish Prickly Pear.” It always has some purple, and when conditions are particularly favorable, the skin may take on a bluish hue. The one in this picture has purple around the edges and around the areoles.

Another “Purplish Prickly Pear” is the Opuntia azurea var parva. It is usually smaller, and paler than its relatives, so it creates a lovely patch of pastel colors in a scene. In this picture you can see the vestigal leaves that appear on new pads of an Opuntia. They are the little upward pointing soft-looking “horns” on this new growth.

Of course there are many, many more species of Prickly Pears in the Big Bend Ranch State Park and the Big Bend National Park, and there are so many hybrids that counting is impossible, but you will probably often see these plants during your walks in the Big Bend.

In the next posting I will cover the other members of this sub-family … the ones we usually call “Chollas.” That post will probably be more strictly accurate than this one but who knows? If you have any corrections to offer, please do. I’d like these posts to be as accurate as possible.

So until then, don’t forget to hug your cacti 🙂

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