When most people think of a cactus, they either imagine a giant Saguaro-like monolith, or a small, clumping Opuntia-like plant. Opuntias are among the most recognizable of all the succulents, if not one of the most familiar of all plants. Despite this familiarity, it is not one of the most grown plants, by a long shot. And perhaps there is a good reason for that. They can be rather difficult plants to love or even to get along with.
As Kelli mentioned in her article, Opuntias have a unique shape and structure of flattened, segmented pads that seem to grow randomly out of each other. Other cacti may have segmented growth like Opuntia, but if they are not flattened, they are either completely unrelated, or are now included in other related genera and USED to be included in the Opuntia. Some other flattened, segmented cacti have also been moved to other genera for picky flower or spine details which I don't even begin to try to comprehend (yet). Some opuntias are monsters, growing over 20 feet tall, while others are barely a few inches high. Most are of a greenish color, but some are brown, grey, turquoise, purple, pale blue, yellow etc. Some have long, lethal spines while others have gazillions of thinner hairlike spines, and some have only the fuzzy, miniscule glochids Kelli mentioned in her article, while yet still others are completely spineless (aka ‘user-friendly'). It is usually the spines that taxonomists use to distinguish this species from that, as well as some floral characterstics. For me, this makes telling apart these plants an ‘art' that I have not come close to perfecting as I have little patience in counting the myriad spines, trying to decide which are central spines, radial spines etc. I prefer to tell them apart by their general appearance... which is why I cannot tell most of them apart.
Review of 'Opuntia Basics':
One of the unique characterstics of Opuntias is they are made of flattened pads growing almost randomly out of each other (see Opuntia arcei in left photo); Other plants frequently labeled as Opuntias but with more tube-shaped 'pads', or fusiform, or spherical etc., as these other two above in a botanical garden have now been put in variouis other genera (center plant was labeled Opuntia leoncito, but is now Maihueniopsis glomerata, and the plant on right is tagged Opuntia caribaea, but is now Cylindropuntia caribaea). So if you see an Opuntia with segments or shapes other than flattened, be suspicious it is no longer in the Opuntia genus.
On the other hand, sometimes freakishly flattened Cacti that are also lumped into the Opuntia genus by many nurseries and botanical gardens turn out to be another genus, too, so be careful assuming all flattened pad cacti are Opuntias. Left: Brasiliopuntia caribaea, middle photo is Consolea nashii and right is Nopalea cochenilifera. At least these are--I think--RELATED to Opuntias...
Also, as Kelli mentioned in her recent Opuntia article, there are two types of spines on Opuntias: the spines and the glochids. The plant on the left shows a few regular spines, and a tuft of glochids in the center (Opuntia aciculata). The plant in the middle shows mostly spines (Opuntia erinacea var. ursina) while the two varieties of Opuntia microdasys on the right have only glochids.
And the above Opuntias either have no spines and almost no glochids (left, Opunita basilaris) or seeming no spines of any kind (center- Opuntia ficus-indica var. decumana photo by Kell), or have only spines and no glochids (that I can see)- right, Opuntia vulgaris variegated. Note: most plants that LOOK like they have no glochids, usually still do, and the smaller the glochids are, the more difficult they seem to be to get out of one's skin, so caution is advised!!
As a group, the Opuntias are often referred to as the "prickly pears," and all Opuntias make these fruits (many are edible)- left Opuntia aequatorialis, center Opuntia robusta; right shows that all the close relatives that USED to be Opuntias also make 'prickly pears' (Cylindropuntia leptocaulis)
Opuntias (and relatives) can be an ornery bunch and many wonder why grow them... but like all cacti, there is a beautiful side to each species that almost everyone can appreciate: the flowers! left- Opuntia basilaris, middle Grusonia invicta (aptly named the Dagger Cholla), right Opuntia 'Baby Rita' (photo by Kell)
and unknown species left, Nopalea cochenilifera middle and Opuntia ficus-indica right
Opuntia monacantha var. variegata (Joshep's Coat) left; Opuntia litoralis var. austrocalifornica (middle) and Opuntia macrocentra (right)
Opuntia polycantha (left- photo by Growin); Opuntia quimilo (middle- photo by CactusJordi) and rigth, Opuntia salmiana
Cylindropuntia acanthocarpa (left), Opuntia stenopetala (center) and Grusonia pulchella (right; photo by CactusJordi)
left: Opuntia x vaseyi (photo acactus); center Tephrocactus alexanderi var. geometricus (photo CactusJordi) and right Cylindropuntia kleiniae (photo by leeann6)
Though Opuntias are fairly easy to grow cacti, they get some parasitic diseases that plague these cacti in certain situations.
Left is an Opuntia infested with a coccineal insect, that, if not treated, can eventually kill the cactus. However, in most cases, it just leaves these plants looking unsightly and unthrifty. This insect is sometimes cultivated on purpose. If you crush one of these white bugs (the bugs are actually not white- the white is some mucoid, almost 'spit-like' protective covering) you will see a bright crimson spot. This dye has been used for a few centuries and is coveted as one of the best natural red dyes available. But if you are not into producing commercial dyes, this bug is a nuisance, and a pretty hard one to control. The white protective layer seems to make it fairly resistant to most chemicals, so these often have to be hosed off forcibly first. Right shows a plant crusted with scale, which can kill Opuntia even faster than the coccineal bugs can. Scale, however, has no upside. And it, too, is difficult to control. However, plants grown in full sun are much less likely to get this bug than those grown in too much shade, so avoiding the shady situations is a good way to keep this from getting out of hand. Again, hosing off of the bugs forcibly is a good place to start, and THEN using some chemical control can be helpful to keep it from coming back. Scale tends to permanently scar these plants so better to avoid than treat.
The Opuntia Species (or at least a few of them):
There are literally hundreds of species of Opuntia. Most grow in the deserts of North and South America, but some are more tropical and some can survive climates where it snows frequently. Below is a brief overview of some of the species of Opuntia I have photographed, many which I have grown and several which I have had other experiences.
Opuntia basilaris (Beavertail Cactus): This is a species native to the southwestern United States, and is very common. This is one of my favorite species partly due to its interesting appearance, shocking-pink flowers and relative ‘user-friendliness'. It is a low plant with thick pads often in the shape of a beaver's tail (hence the name) of a dull blue-green, pale green, pinkish to purplish color and nearly spineless (even the glochids of this plant are relatively user-friendly). I have some growing on my property in the Antelope Valley in southern California that I did not plant there... it's my first plant native species on my property that I actually like!
Opuntia basilaris shots from plants in botanical gardens in southern California. Right is a weird, short-fat pad form called Opuntia basilaris var. brachyclada.
These Opuntia basilaris are native plants in my area and shots of naturally occuring plants in my very own yard!
Opuntia echios- Tree Prickly Pear: One of the rarer native cacti to the Galapagos island, this is a potential monster with a potential maximum height of thirty feet. I have never been to the Galapagos, but I have seen several of these at botanical gardens and they are one of the most densely spined Oputnias I have seen. I include this one because it is interesting in comparison with the relatively spineless dwarf of a cactus, Opuntia basilaris.
Shots of Opuntia echios in a botanical garden in Santa Barbara (Lotusland) showing intesne spination and a tall overall plant (these plants are still very young)
Opuntia englemannii var. linguiformis- Cow's Tongue Prickly Pear: This is a large shrubby species and, to me, the most ornamental variety of the species, with irregularly shaped, flattened, thin pads (that look a bit like a cow's tongue).
Opuntia englemannii var. linguiformis at a botanical garden (left) and two shots of a plant in neighbor's back yard (middle and right)
Opuntia eglemannii var. lingiformis flowers and fruits (left and center); another interesting form of Opuntia englemannii- variety subarmata (right)
Opuntia ficus-indica var. decumana- Smooth Barbary Fig: This species is one of the most economically important of the genus (see another article by Kelli: http://davesgarden.com/guides/articles/view/4238/) and this form is one of the more ornamental and user-friendly of all the cacti. I have grown this one and it is easy (though tends to topple over once it grows over eight to ten feet tall). It has no spines at all (that I have seen)- not even glochids (at least none worth mentioning). This makes it one of the better species to use in cooking, feeding desert tortoises, or planting near a walkway since it is attractive and completely user friendly.
Opuntia ficus-indica normal form used as a hedge (left); Opuntia ficus-indica var. decumana photos (center in a botanical garden, and right in my yard)
Opuntia fragilis (Brittle Cactus) this is one of the more dwarf species of Opuntia and has one of the best cold tolerances of all the cacti (down to zone 4a, or -30F). It has variable spines (long to almost non-existent) and is also very ‘fragile', losing its somewhat egg-shaped pads easily when moving this plant, or just bumping into it. It spreads easily this way, grabbing onto animals that venture too close, a pad tears away, gets a short ride, and re-roots where ever it's deposited. As a child I certainly did my part in moving this plant around to new areas inadvertently, as it hitchhiked on my socks while I would carelessly lumber about the local wilderness in New Mexico- not one of my fonder cactus memories.
Opuntia fragilis shots (middle photo Ally_UT, and right is a plant in Canada, by kennedyh)
Opuntia gosseliana- Violet Prickly Pear: one of my favorite species is this brilliantly colored plant, with turquoise pads that turn a nice, pinkish-violet in stressful conditions (cool, dry etc.). There are several other violet species (Opuntia macrocentra and Opuntia 'Santa Rita') that I have a difficult time telling apart- all make great landscape plants of remarkable ornamental value. Opuntia macrocentra is the plant featured at the start of this article
Plant labeled as Opuntia gosseliana left; Opuntia 'Santa Rita' middle showing changes during drought (center); right is plant labeled as Opuntia gosseliana var. Santa Rita (obviously I am not the only confused)
Opuntia 'Santa Rita' showing particularly nice color changes (left); Opuntia macrocentra 'extra spiny' in a show (center) and right showing color changes with stress
Opuntia microdasys (Bunny Ears)- There are many forms of this popular landscape plant and I have grown several of these varieties in my own garden. They have a fuzzy, velvety almost soft, comfortable look that is quite the opposite of reality. These are among some of the plants I dread dealing with the most, and I grow a LOT of spiney, toxic and dangerous plants. This species and all its varieties have no long, scary, needle-like spines, but are covered with gazillions of dinky, harmless-looking, adherent glochids that come off in thousands with the lightest brush or touch. These dislodged miniscule spines weigh about the same as motes of house dust and quickly become impaled in clothing, skin and exposed mucus membranes making any subsequent movements painful and annoying for hours or even to days to come. I love the look of these cacti, but I never want to have to move or prune one again.
Opuntia microdasys shots
Opuntia microdasys var. rufida (left) and 'Funny Bunny' (center)- both plants in my collection; right are seedlings of several varieties for sale at nursery down the street from me
Opuntia phaeacantha (New Mexico Prickly Pear, among other names): This is another childhood nemesis of mine and has wounded me numerous times throughout my youth as I hiked about northern New Mexico (where I was born and raised). It is an only very slightly ornamental, small, shrubby, sneaky species (likes to grow in other low scrub and ‘hide') with long, sharp spines that easily pass through sneakers (my perennial hiking gear). Europeans report this is one of the easier cacti to grow in cool, moist climates where most other Opuntias suffer. Lucky them!
Opuntia pycnantha This is not a common species, but one of my favorites due to its amazing ornamental appeal. It not only has attractive rust colored spines and nice, neat, dense patterns on the pads, but it tends to grow somewhat symmetrically, at least compared to most randomly growing Opuntia species, making it an exceptional Opuntia for pot or small garden culture. Unfortunately it is not one of the more cold tolerant species and though I have planted it in my new home in the Anteleope Valley, I am pessimistic about its long term survival there.
Opuntia pycnantha in my collection (left) showing flower; nice clump in collector's garden center; and a particularly nice, symmetrically grown plant in a cactus show (right)
Shots of Opuntia pycnantha pads showing nice even rows of spines. Mature pad on left and new, extra fuzzy immature pad on the right
Opuntia robusta (Dinner Plate Cactus) This is another favorite of mine, having large, almost completely circular, thick pads almost a foot in diameter--very robust. The ornamental value of this species is exceptional but you need a large space to grow this one.
Opuntia robusta colony (left); center showing fruits and right showing a rooted pad with some new growth at the top. Most Opuntia species are easy to root from single pads like this
Below are more Opuntia examples I have seen about southern California just to give you some idea of the variety available in cultivation
Opuntia cochenilifera (a variegated form) left; Opuntia durangensis (center); Opuntia vulgaris (right), one of my favorite in terms of ornamental look and nice spination
Opuntia ellisiana left, a large, variable species (this one circular and nearly spinelss); Opuntia macbridei center (a very low growing, clumping minature species); right Opuntia streptacantha- one of the larger species
Opuntia chlorotica left, another of the nice pale blue species; center is Opuntia rufida, and nice neat plant with few spines, but nasty glochids; right is Opuntia dillenii, another large species
Opuntia galapagei (left) and Opuntia megasperma (center) are two more species native to the Galapagos islands; right is Opuntia pailana, a species with very long spines.
There are MANY more species of Opuntia, but these are among my personal favorites (or least favorites). The following are a few examples of other cactus species that USED to be in the Opuntia genus, or are very closely related genera.
The Opuntia Relatives:
Austrocylindropuntias and Cylindropuntias are genera that many texts and resources still include in the Opuntia. But these plants are notably tubular, rather than flattened. The Cylindropuntia are common shrubs throughout much of the southwest and are known collectively as Cholla (pronounced Choy'- ya). Cholla are another childhood nightmare plant, and I have spent many hours during hikes about New Mexico attempting to pull these spines out my arms and legs. The spines of many Cholla are barbed, making pulling them out of tissue a very difficult and painful undertaking. Jumping Cholla are the worst with entire cactus limbs quickly adhering to a passerby who barely even touches them (they seem to ‘jump' onto you) and quickly becoming impossibly impaled onto any available surface.
Cylindropuntia in my back yard, C. acanthocarpa (left)- a local native; middle Cylindropuntia echinocarpa and right, Cylindropuntia bigloveis (Jumping Chollas)
Cylindropuntia californica (left), Cylindropuntia fulgida (center), another Jumping Cholla species; and Cylindropuntia leptocaulis (right)
The Austrocylindropuntia are pretty similar but are the South American cholla versions of the shrubby, tubular cacti. There are other minor differences, but not ones I can really pick out easily. Some Grusonia can be 'cholla-like' as well, but tend to be pretty small in comparison to these other two genera.
Austrocylindropuntia subalata (Eves' Needle), a common species, left; Austrocylindropuntia pachypus (center), Austrocylindropuntia atroviridis in a plant show right
Consolea, Brasiliopuntia and Nopalea are more very Opuntia-like genera of cacti with remarkably flattened pads. Most of these are tree cacti and get quite tall. The species I am most familiar with and have grown before is Consolea rubescens, or Road Kill Cactus. It is a fairly ‘user-friendly' species with minimal spination and a remarkably flattened appearance (as if run over by a truck). Nopalea cochinillifera is another one I have grown and it has a nice globoid overall shape to the entire shrub, is fairly user-friendly as well, and has some of the most shocking pink, oramental flowers of all the Opuntia-like cacti.
Young Consolea rubescens (Road Kill Cacti) left, and a tall one in the desert middle; right is Consolea falcata, showing this genus can grow into a large tree
Cumulopuntias and Tephrocacti are dwarf, segmented genera with more spherical than flattened pads, making them some of the more popular genera for ornamental pot culture. The Tephrocacti, in my experience, are one the nicest small potted cactus genera, but reallly prone to fall apart thanks to their very weak segemental attachments... large specimens like one below are extremely hard to keep from falling apart and need to handled with extreme care to keep them all together.
Cumulopuntias corotilla (left), dactylifera (center) and pentlandii (right)... a lot of these look the same to me, and hard to tell from some of the other genera (such as Maihueniopsis)
Tephrocactus articulatus var. diadematus, or sometimes known as the Pinecone Cactus, a very popular and easy to grow (and user-friendly) species left; one of the most ornamental of all cactus (and this one an overall show winner) Tephrocactus alexanderi var. geometricus center; Tephrocactus molinensis right
Tephrocactus articulatus var papyracanthus, or Paperspine Cactus left, another very popular species; Tephrocactus alexanderi center and Tephrocactus weberi right
Grusonia, Tunilla, Pterocactus and Maihuenia (and closely related Maihueniopsis) are several more dwarf cacti sometimes lumped into the Opuntia as well
Grusonia moelleri (left), Grusonia bradtiana (center) and Grusonia invicta (aka the Dagger Cholla- right)
Pterocactus fischeri (left); Pterocactus tuberosus (center); and Pterocactus australis (right)
Tunilla soehrensii (left) and Tunilla corrugata (right)
Maihuenia poeppigiana (left) and Puna clavaroides (right) are both very popular species for pot culture and most growers still list them as Opuntias
Maihueniopsis bonnieae (left) and Maihueniopsis subterranea (right)
For more on Opuntias, check out this website.