7/27/2019 The Genus Opuntia & The Genus Echinocereos

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THE GENUS OPUNTIA

In the creosote-bush/ lechuguilla/ sotal/clumpgrass flatlands around Henry at K-

Bar, three species of pricklypear cactusare abundant; their names are:

Englemann Pricklypear , Opuntiaengelmannii 

Brown-spined Pricklypear , Opuntia phaeacantha

Purple-tinged Pricklypear , Opuntia macrocentra

 As the picture at the right shows, pricklypears look like green, spiny, beaver tails stacked one atop the other, growing in sprawling clumps. Folks around Amistad lump together the Englemann and Brown-spined Pricklypears under the common name of nopal. However, both of these species havedifferentiated into several taxonomic varieties. Here I've often thought that I'dfound what was for me a new species of pricklypear only to discover later thatit was only variety of the Englemann or Brown-spined Pricklypear.

Especially on rocky slopes a remarkable non-prickly pricklypear appears --one with no long spines! It's called the Blind pricklypear , Opuntia rufida.Mostly a Mexican species, it enters the U. S. only in Texas along the Rio

Grande. This species takes its common name from the fact that despite itsspineless condition it is abundantly equipped with tiny glochids. A superstitionholds that wind carries these glochids into animals' eyes, blinding them.

Pricklypears belong to the genus Opuntia. As with most flowering plants, thespecies are defined mostly in terms of flower and fruit anatomy -- notcharacteristics of vegetative, or stem, parts. In the genus Opuntia t his isespecially apparent because many of its species, while bearing flowers andfruits typical of the genus Opuntia, possess stems that don't at all look like"stacked, spiny beaver tails."

One large group of non-flat-stemmed Opuntias is the cholla group, themembers of which look like stacked, spiny cucumbers or pencils. Dog-Billintroduced us to the Christmas cholla, Opuntia leptocaulis. The samespecies grows here, though at Big Bendit is referred to as Tasajillo.

 Another cholla found here is the Cane Cholla, Opuntia imbricata, growing sixto eight feet tall.

Yet a third general class of Opuntia consists of several species looking like joined-together, very spiny, longish egg slying on the ground. Usually thesespecies' joints are so loosely attached to one another that if a trouser legbrushes against them entire joints come loose and stay stuck tothe cloth untilthey are knocked off. These disarticulated joints can root and form new plants,

7/27/2019 The Genus Opuntia & The Genus Echinocereos

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so their weak joint-connections constitute part of the plant's dispersal strategy. Often these speciesare not noticed until it's too late. The member of this group that I've found here fully deserves itsname --the Devil Cactus, Opuntia schottii .

In review, at Big Bend I've seen seven species of the genus Opuntia-- four pricklypears, two chollasand one devil cactus.

THE GENUS ECHINOCEREUS

The next-largest genus of cactus found during my walks here isEchinocereus, which usually is easy to recognize because its spines arisefrom atop ridges extending up and down the cylindrical cactus body, andsometimes spiraling around it. The most common Echinocerei found here arethe:

• Strawberry Cactus, Echinocereus spp, growing in round, compactclumps about one foot high

• Rainbow Cactus, Echinocereus dasyacanthus, about a foot tall andalmost white because of its mantle of short, sometimes multicoloredspines

• Pitaya, Echinocereus enneacanthus, similar to the Strawberry Cactusbut larger and with fewer spines

• Brown-flowered Cactus, Echinocereus chloranthus, which I was

calling a rainbow cactus until a flowering specimen was found• a little Echinocereus that's so uncommon that it has no common name;

it's Echinocereus russanthus

THE GENUS ECHINOCACTUS

You'll remember the Horse-crippler, the cactus at Amistad with only its amplyspiny crown exposed at the ground's surface. That cactus, which I've notfound here, is a member of our third big genus, Echinocactus. That genus isfamous for it's heavy spines and roundish bodies. Echinocacti are known asbarrel-cacti, and often grow quite large. The largest cactus seen so far is an

Echinocactus.

The most common Echinocactus I've found here is the Eagle Claws Echinocactus horizonthalonius, shown at the right.

The Giant Fishhook, Echinocactus hamatacanthus, is a fairly rare speciesusually found on rock ledges. It's about two feet high and a foot thick, barrel-shaped, and bears reddish spines up to six inches long diabolically hooked attheir tips. Just think of what happens to a deer poking its nose into a GiantFishhook cactus, then trying to withdraw...

THE GENUS MAMMILLARIA

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The last big genus is Mammillaria,which takes its name from the Latin wordmamill ,meaning breast or teat. Visualize this: A cluster of jalapeño peppershas its peppers' broad, round bottoms pointing outward so that the cluster looks something like a green, bumpy ball. Then attach clusters of radiatingspines atop each of the exposed pepper-bottoms. Now you have a cactus of 

the genus Mammillaria.

Weniger reports two very descriptive English names for my favoriteMammillaria found here -- Nipple Cactus and Little-chilis. It's Mammillariaheyderi .

The second Mammillaria found here, this one seen only in one area alongTornillo Creek, looks as if it has been gnawed on by rodents. Its lower partsare incrusted with white, corky callus. This corkiness is natural. I'm not sure of what benefit it is to the cactus. This species is called Cob Cactus,Mammillaria tuberculosa, because the corky material causes it to look

something like a shelled corn-cob.