The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Thursday, April 24, 2008

Cacti Produce Some of Our Most beautiful Flowers
by Ro Wauer

There is a marvelous cactus flower in our yard near Mission Valley. I planted it several years ago, and it annually produces several magnificent blooms. The flowers, about two inches across, have golden yellow petals. And each pad has widely spaced aeroles containing grayish spines about 2 inches long. This cactus is best known in Texas as Texas pricklypear, although it often goes by its original name of Engelmann pricklypear.

The Texas pricklypear is the most common and widespread pricklypear in Texas, although botanists have identified a total of 20 pricklypear species in the state. And there are 13 kinds of chollas, closely related species with the same genus name of Opuntia. Pricklypears possess flattened pads while cholla pads are cylindrical, rounded in cross-section. Although the majority of pricklypears look somewhat alike, chollas can vary from tall species such as cane cholla and tasajillo to those that sprawl on the ground, such as dog cholla.

Cacti or cactuses, both terms are correct, are some of our favorite plants, and they can occur from the lowest and hottest areas in Texas to near the summit of our highest mountains, such as the Chisos, Davis, and Guadalupe mountains. And cacti have been divided into at least 19 groups. Easiest of these to identify is the pricklypear/cholla group, while others can be difficult, maybe because the various cactus books seldom agree. Other groups that can usually be identified include the fishhooks, living rock, star cactus, barrel cacti, hedgehogs, and nipple cacti. And too often some of the other spiny plants are misidentified as cacti. Examples include yuccas, agaves, acacias, and ocotillo.

As near as I can determine, 88 cactus species occur in Texas. And approximately 140 forms or subspecies have been identified. But these numbers are somewhat ambiguous. Cacti hybridize readily, influenced by various environmental factors, but also because few botanists can agree. For instance, our Texas pricklypear (Opuntia engelmannii) has five subspecies. And the common and widespread claret-cup (hedgehog) cactus (Echinocereus coccineus) also has five subspecies.

What is amazing to me is, that of 88 cactus species in Texas, 23 of those are endemic, found nowhere else but in Texas. Seven of the 23 are hedgehogs, six are cob cacti (genus Coryphantha), three are pricklypears, two are chollas, two are of the genus Echinomastus, and there are three unrelated species of the genera Epithelantha, Ferocactus, and Neolloydia. The non-Opuntia cactus species vary greatly, but their aeroles are positioned along ribs or on tubercles. Although most of the unique Texas cacti occur only in the Trans-Pecos portion of the state, particularly in the Big Bend and Davis Mountains area, a few are known only from the Hill Country, the Pineywoods, or the Lower Rio Grande Valley. None of the endemic species can be found along the Gulf Coast.

Cacti are native only in the Western Hemisphere, except in Alaska, Hawaii and Maine. They are as American as corn, tomatoes, tobacco, and potatoes. But today cacti can be found almost worldwide, having been introduced elsewhere as early as the Columbus voyages to the New World. By the 1800s, cacti because so popular in many parts of the world that a number of cactus trading companies evolved, and propagation of cacti became big business. The cactus hobby continues today, and botanists are still trying to understand what plant is what. However, since the use of DNA, those relationships are becoming much more precise. Soon it will be time for the plant taxonomists to reach agreement. But in the meantime we can all enjoy the short-lived cactus flowers for their beauty.


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