Opuntia Blog

Cotyledon sp. flower, by Eric Hunt, click on image to see gallery of images by Eric Hunt

The genus Cotyledon (family Crassulaceae) has a dozen or fewer species, but it used to have many more. Over time various groups have been separated out including:  Adromischus, Dudleya, Rossularia, and Adromischus. The various Cotyledon species are mostly found in South Africa. The plants are generally small, woody srubs with succulent leaves that are found in rocky soils or even on cliffs. Some of the species have woolly leaves, and others have leaves with a glaucous bloom.

Cotyledon orbiculata is a promiscuous weedy plant in South Africa, and is listed as a weedy plant in the Global Compendium of Weeds. However, C. orbiculata thrives in a Mediterranean-type climate and only becomes weedy in certain frost-free areas. Other Cotyledon species are generally not considered to be weedy.

Crassula ovata (formerly Cotyledon ovata)  is a widely grown house plant. The plant is tolerant of indoor, dry conditions and low light but eventually will become etiolated in dark positions. The plants are easily over watered, especially in the winter when growth slows or stops. C. ovata is an excellent candidate for a covered patio as long as it has winter protection from frosts.

Cotyledon orbiculata, by Noodlesnacks (Wikimedia), click on image for larger photo

Neoraimondia qrequipensis flower, by Craig Howe, click on photo to see larger image

Neoraimondia arequipensis is one of many Peruvian endemics. The plants can be tall, but typically branch from the base (low on the plant). Spines from the plant were formerly used to make fish hooks; young spines were bent into a hook and allowed to mature. Unlike many cacti, N. arequipensis may produce spines or flowers from individual areoles for years (EF Anderson, The Cactus Family, Timber Press, 2001).

N. arequipensis was apparently first described (as Cereus arequepinsis)  in 1834 by Franz Meyen. The species is variable,. A number of varieties and species have now been combined into N. arequipensis, including: N. aticensis, N. gigantea, N. peruviana, and N. macrostibas (D Hunt, N Taylor and G Charles, eds, New Cactus Lexicon, DH Books, 2006). Also, N. arequipensis (or its various forms) was once referred to as C. arequipensis, C. macrostibas, or Pilocereus macrostibas.

Neoraimondia arequipensis, Chaparri Nature Preserve near Chiclayo, Peru, by Craig Howe

Austrocylindropuntia pachypus, click on link to see original Web page for Jardin Botanico

Austrocylindropuntia pachypus is a Peruvian endemic; it is found in no other country. I don’t know much about the plant, but you can find a bit more about it at Cactaceae endemic of Peru. I think it is a low-altitude plant, perhaps growing now higher than 3,000 to 4,000 feet.

A. pachypus is little studied, and all the printed literature I could find was in Spanish. More images may be found at CactiGuide.com.

A. pachypus has been known as Maihueniopsis pachypus, Cylindropuntia pachypus, or Opuntia pachypus.

Dracaena cinnabara tree, image from Wikipedia, click on the image to see the original (large) image at Wikipedia

Dracaena cinnabari is not a cactus, but it is an amazing plant. D. cinnabari is endemic to Socotra Island in Yemen. Its common name, dragon blood tree, derives from the reddish sap obtained from the tree that is used as a dye or a medicine. Wikipedia reports that the red resin was used in dying wool, gluing pottery, as a breath freshener and as a lipstick. Purportedly, the red sap has been employed in magic rituals.

Some sources suggest that D. cinnabari was widely distributed over Socotra Island in the past, but while it is still widespread, it is in scattered populations. It is not clear why overall numbers of the tree have declined because Socotra Island is not yet subject to typical ecological pressures (eg, urbanization, ranching). The trees typicall grow “areas affected by the mists, low cloud and, in particular, the constant drizzle of the monsoon.” Perhaps such areas are not as common as in the past? One source reports that there is circumstantial evidence of drying in the region over the past few hundred years.

You can find out more about D. cinabari at the Arkive. 

Xoconostle fruits, click image to see original advertizment

El Universal is a newspaper in Mexico. I don’t often read it, but sometimes I enter the URL into Google and then ask for a translation. It is interesting and fun to read about events in our large neighbor to the south (population about 110,000,000).

Recently I saw an advertisement for xoconostle in El Universal; xoconostle are a special type of Opuntia fruit. The fruits are sour (acidic) but wonderful in cooking. Additionally, the seeds cluster in the interior of the fruit; they are not dispersed as is the case for the fruits of many Opuntia species. Because they are clustered, they can be easily scooped out for fruit preparation. Xoconostle are only produced by a few Opuntia species (eg, O. matudae, O. oligacantha, O. leucotricha, and O. jonocostle). 

Xoconostle fruits can be used in many dishes from salsa, to jam, to hot dishes (even with beans), or breads. Often, xoconostle fruits are used in sauces or as condiments (even pickled). Xoconostle fruits are even used in beverages, sometimes with honey and lemon.

The Atacama Desert in northern Chile runs along the coast and extends inland to the base of the Andes Mountains; the desert is about 50-100 miles wide and about 600 miles in length. The Atacama Desert is one of the driest places on earth; it is estimated that some parts of the desert have not received rain for 300 years. The Atacama Desert has relatively mild temperatures (not as hot as other deserts, nor as cold). Rivers from the Andes Mountains cut across the desert at different places, taking their water to the Pacific Ocean.

Several Web sites provide stunning images of cacti in the Atacama Desert, including the site of Gerhard Hudepohl.

Though rain is scarce, a million or more people live in the Atacama Desert; they are mostly clustered along the Pacific Ocean coast and use rivers for their water sources. Fishermen and miners can be found in the various towns and villages.

Many parts of the Atacama Desert are too dry to support any plant life, but some areas receive a little rain each year. In some areas of the desert, ocean fog provides moisture for plants and animals. Closer to the mountains, there is more precipitation than is found in the center of the desert.

Unidentified cactus in the Atacama Desert, photo by Andrew Dunn

Cacti of the Desert Southwest, book

Amazon.com offers a seemingly endless supply of books. Recently, I purchased a small book called Cacti of the Desert Southwest. I paid just about $4.00 plus postage to purchase the book used from a bookseller. Sometimes the new book price is just too expensive, but other times Amazon.com offers a discount. But, the new book price seldom beats the used book price. I’ve had nothing but success when I’ve ordered used books–no problems and delivery has been within a week or two.

Cactus Candy

Cactus candy is a novelty that is offered by a few candy stores. If you are brave (and want to handle an Opuntia cladode), you can make your own candy.

RECIPE
Use a sharp knife to remove spines and epidermis from 1 or 2 large Opuntia cladodes. Cut the skinned cladode into squares (about one-half to one inch). Pour cold water over the squares and soak overnight in a large excess of water at room temperature. Change the water and gently simmer the  squares until they are tender. Drain the squares and heat slowly in the prepared syrup until most of the syrup is absorbed; drain the squares. Roll the squares in sugar (powdered or granulated).

Syrup
Dissolve 3 cups of sugar in 1 cup of water over low heat until sugar is completely dissolved. Add 2 tablespoons orange juice and 1 tablespoon lemon juice. Use red food coloring if desired.

You can read more about cactus candy here. You can order cactus candy at the Cactus Candy Company.

Opuntia stricta seedlings, photo by Danny Green

Cactus seedlings generally can’t endure the conditions that mature plants can take in stride. Seedlings are sensitive to too much heat, sun, wind, and cold, as well as lack of water. Additionally, seedlings are more susceptible to grazing by insects and animals. Most cactus seeds never produce a cactus plant; they may germinate but very few live to produce a mature plant.

Many factors affect seed germination including temperature, moisture, and mechanical scraping of the seed. But, germination is just one aspect in plant reproduction. Seedlings must be able to survive and reproduce. Likely, many cactus seedlings only survive when special years occur, years with extra water or mild temperatures. Probably two or tree such years in a row are necessary.

One study showed that one in 20,000 Opuntia rastrera seeds survives to produce a plant in a grassland setting. The success rate is even worse in scrublands where one in 7,000,000 seeds produces a plant.

The photo in the blog post shows a cactus seedling, grown under fluorescent lights and about 3-4 weeks old. The cotyledons are reddish, and sort of pointed to the left or right. They are not the typical cotyledons of a radish or other plant, rather, they are much reduced. The seedling is tiny, about 4-5 mm tall.

The “real” cactus is tinier still and sits at the top of the seedling; it is the white, fuzzy bit between the cotyledons. In time, the white, fuzzy bit will grow and become the cactus we are more familiar with.

Lobivia seedling, 3-4 weeks old

I hope a reader can help me identify this cactus; I think it is a type of Mammillaria. I don’t usually buy unnamed cacti, but this one was on sale for about $1.50 at Home Depot, or Lowes, or a similar megastore. There were several cacti and I though I’d try some out for cold hardiness.

I bought the plants when night dipped to about 35 F, and I left them on my patio for weeks while the nights grew progressively colder. When temperatures dropped to 20 F, I checked the plants and they were fine. Then, I left them out when temperatures dropped to about 15 F, and finally to about 10 F. Two cacti died, and the one depicted here survived. I don’t think the temperature was really 10 F on the patio because it is a covered patio and because the little cactus plant was next to the house wall, but it got pretty cold.

Unidentified cactus

Stuart in the snow

I live in Maryland and, since leaving Texas, I haven’t had an outside garden. So, I grow cacti on my patio, or in the house under lights (in winter). Next year I hope to have a few more plants in pots that I can leave out for the winter (or most of the winter). 

We’ve had a lot of snow recently in Maryland, and it’s just as well I don’t have many plants outdoors because I wouldn’t be able to find them. There was about 2 foot of snow before Christmas, and recently another 30 inches. More snow is forecast for tonight.

I don’t have a photograph of cacti in the snow, but I do have a photo of my dog in the snow. He was happy to get into the house after the picture was taken. You can find actual pictures of cacti with snow here, and here.

Garden Soil

A brief discussion on a cactus email list recently got me thinking about potting soil for cacti: to sterilize or not to sterilize. This is a topic that stirs passions.

For what it’s worth, I don’t use sterile soils in my potting mix, but I use “clean” ingredients. Thus, for small amounts of soil I use packaged potting soil (typically a loam with compost) as a base. I mix the base with coarse sand and with perlite or pumice. For general use I add each part in equal volumes. Because I use packaged and/or composted ingredients, I don’t worry about insect eggs or fungal inoculum, and I don’t heat treat the ingredients.

However, if I used soil right from the garden (as in the photo) I’d be sure to bake it for 2 hours or more at 200 degrees F (about 93 C) to kill insects and some pathogens. If I threw in a handful of compost (from the compost pile) and I wouldn’t bother to heat treat the compost because I’m happy with the “cleanliness” of composed ingredients.

Other folks feel differently about the matter and don’t take special efforts to kill organisms in their potting soils, heating or composting. I guess that, whatever works for you is what you should do.

This lovely photo came labeled as Trichocereus formosus. So, my question is, what is the name for this plant when it is considered as a member of Echinopsis?

Note added later: Trichocereus formosus is known as Echinopsis formosa. However, a reader points out that the plant in the picture is probably a hybrid.

Unidentified Echinopsis

Herbertia lahue, Columbus-LaGrange, Texas

I don’t usually think of the pretty Herbertia lahue as a desert flower, but I have found it growing with Escobaria missouriensis, Opuntia lindheimeri, O. macrorhiza, and Cylindropuntia leptocaulis. The cacti were mostly at the east edges of their ranges, and H. lahue was at the western end of its range. H. lahue was growing between Columbus and LaGrange, TX.

H. lahue has beautiful 1-day flowers, but the plant flowers for a month or more making it worthwhile to grow. It can dust pastures with pale blue in the Spring because the plants are so numberous in and around LaGrange.

H. lahue is really not a desert flower because it grows across southern Louisiana and along much of the Texas Gulf coast. But the area (at least in Texas) is subject to extreme drought sometimes–so H. lahue survives as a bulb. In contrast, cacti survive the drought of coastal Texas with their own cactus adaptations (lack of leaves, waxy cuticle, etc.).

Lobivia species, under lights, from Miles' to Go

I’ve ordered plants off and on from Miles (Miles’ to Go Nursery) in Arizona for over 10 years. The plants always come quickly and always arrive in very good shape. Additionally, most of the plants are of blooming size if they bloom while in a small pot.

Miles must get his plants in and keep them a while because he’ll advertize a plant as 3-inches and it will arrive and be nearly 4-inches across or tall. The plants are not expensive, typically $4.50 to $6 for the things I might order (Gymnocalycium, Lobivia, Rebutia, etc.).

Miles offers some cold-hardy plants but he doesn’t feature them as especially cold hardy. For instance, he sells several types of Gymnocalycium that will surely survive 10 F, but he doesn’t mention the fact. Similarly, he sells a variety of cold-tolerant Coryphantha, Escobaria, Echinocereus, etc. In fact, Miles sells many genera but few or no Opuntia.

What do all the following names have in common? Apparently all of them have been used at one time to describe Parodia, or a species of Parodia. That is a lot of names to go around for a genus of about 50 species. Read more about Parodia here.

• Acanthocephala
• Brasilicactus
• Brasiliparodia
• Brasilocactus
• Chrysocactus
• Dactylanthocactus
• Eriocactus
• Eriocephala
• Friesia
• Hickenia
• Jauhisoparodia
• Malacocarpus
• Microspermia
• Neohickenia
• Notocactus
• Sericocactus
• Wigginsia

Parodia herteri, image from Wikipedia

Agave americana

Agave americana is not particularly cold hardy, but if you are lucky enough to live in an area where it grows you can appreciate its beauty. Most forms of the plant seem to be reliably hardy to 10 F or 15 F, but Plant Delights Nursery sells one form (ssp. protoamericana ‘Blue Steel’) that is reported to be hardy to below 10 F.

If you live in cold areas you can always grow A. americana as a pot plant; it takes to large containers and will sit quietly for months if you have a dry and cool place to overwinter it (as in a garage). The wonderful thing about A. americana is that it is seemingly impervious to too much water and rain, so it is sometimes seen in Southeast gardens.

Colors vary in A. americana, but most forms are blue-gray or blue-green. The big leaves and unusual color make this a handsome accent plant.

Delosperma seedlings, various types, seedlings germinated 4-6 days earlier and are in 3-inch pots

I ordered Delosperma seeds from HardyPlants.com and from Mesa Garden. Both sets of seeds arrived quickly. The seeds from HardyPlants.com were more expensive but there were 50 or more per packet, whereas the Mesa Garden packets held 20- 30 seeds. However, Mesa Garden offered a broader selection of cold-hardy Delosperma seeds. Not many places sell Delosperma by mail, much less seeds.

The seeds were tiny, very tiny. It was difficult to count them because they were so small. I sprinkled the seeds over a mix that I use for many cacti and succulents: one-third top soil, one-third small perlite, one-third coarse sand (builders’ sand). I watered the seeds from below and set them under fluorescent lights (about 8-10 inches from the bulbs). I kept the seeds at room temperature.

I thought I saw tiny seedlings by Day 5, and on Day 6 I counted multiple seedlings. The seeds pots have been under lights for about 11 days now and the Delosperma seedlings are still at the cotyledon stage. But, they are growing a bit each day and seem happy–I’ve started to remove the saran wrap cover and expose the seedlings to 2-3 hours a day of not-so-humid atmosphere.

You can read more about Delosperma here, here, and here.

Opuntia species can be pests in grazing lands. Sometimes the plants become very numerous and crowd out desirable forbs and grasses. Controls for weedy Opuntia are various but are often ineffective. One strategy to control Opuntia is a prescribed extreme burn; the use of limited (but hot) grass fires to destroy Opuntia species.

One study reports,

“A central prediction of our research is that extreme fires will serve as an economically and ecologically preferable management tool for controlling problematic Opuntia populations…”

Opuntia lindheimeri in experimental burn plot near Sonora, Texas, fire damage visible in background, photo by Bill Rogers

Cactus seedlings, click on image to see original photos (large size) at Flickr

Cacti are tough, and they can go months without water even in hot sun. Cacti are made to endure. But, it is a wonder how seedling cacti ever get started–they are tiny and dry out easily, and they don’t like hot sun.

For sure, many seeds germinate in the shade of their mother plant, or even in the shade of a shrub or a rock. The light is bright but not direct hot sun.

For water, it seems likely that most seedlings don’t germinate until there has been a fair bit of rain, and the soil is saturated with water. Even so it seems probable that most seedling cacti don’t make it, only those that germinate in “exceptional” years can survive. Exceptional years are those with extra rain and (perhaps) cooler temperatures. Some cactus might even need two exceptional years in a row.

However, that is not so unusual for plants that live many years. Cacti can survive for decades and if they only have “exceptional” years every 10 or 20 years then they’ll still have a chance for their seeds to germinate.

Petunia in her sundress

Petunia is a little Chihuahua, just about three pounds. She loves to sun herself underneath a big Opuntia that grows in my old yard. When I get home from work she throws herself into a happy fit and runs around to the front of the house to see me, but if the afternoon sun is still shining she’s soon back by her Opuntia.

Cut cactus showing callus, click image to read original article

I found a nice article about cuttings on the WWW. It has great photos of callused cacti, of agave proliferations, and cactus cuttings. The article also describes how to grow cacti and succulents from seed, but it is the photos of the cutting process that interested me.

You can access the article (with color photos) here.

Sample graft from article

The World Wildlife Fund has prepared an interesting article that you can read here. It is concerned with “Trade and Conservation of Chihuahuan Desert Cacti. The article describes plants in Texas, New Mexico, Arizona, and Mexico that are vulnerable to overharvesting. Even Opuntia are vulnerable because they are harvested unsustainably for use in cosmetics.

Most of us, as cactus growers, only grow seed-grown plants from reliable dealers, but a blackmarket trade continues across international and state borders.

“World Wildlife Fund (WWF) considers the Chihuahuan Desert Ecoregion (CDE) of Mexico and the United States an important ecoregion for conservation because of its outstanding biological diversity, ecological fragility, and environmental concerns. The ecoregion, rich in natural resources, faces a range of visible threats stemming from human activities such as mining, fossil fuel exploration, livestock grazing, industrial agriculture, and development.”

Cactus Climber for Cats

If you like cacti, and cats, this product may be for you. In any event, it is likely better than letting your cats climb a cactus. You can read about the product here.

“This attractive tree incorporates a 5-inch wide ledge within each of its 6 arms. The arrangement of these arms allows cats to climb up and down the tree. A wide base ensures that the unit will not topple over under normal circumstances.”