Opuntia Blog

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

Opuntia ficus-indica, proposed for fighting desertification

Opuntia are considered a weedy species in many countries where they are not native, especially in the Mediteranean, Africa, Asia, and Australia. The plants have overrun farmlands and degraded natural habitats. However, at least sometimes, Opuntia are considered allies in the fight against the spread of deserts.

A newspaper reports that,

“The Federal Government has recommended that “Cactus Opuntia” plant should be used to combat desertification in Nigeria, Minister of Environment Mr John Odey has said.

He made the statement on Tuesday in Abuja at a sensitisation workshop on the “Utilization of Cactus Opuntia to combat desertification, organised by Interact Safety System Ltd.He said that the plant was selected, due to its potential in erosion control and land rehabilitation, especially in the arid and semi-arid zones of the country.”

I guess that one man’s poison is another man’s food. Read more about the use of Opuntia to fight desertification here and here.

Tortoise, Texas (Gopherus species)

Cacti grow in many places, but often the surrounding country is beautiful and desolate. If you follow the link here, you can see some great images from the American Southwest. All the images feature cacti, or were taken near cacti.

Baboon feeding on Opuntia fruit, click image to access original Web page, photo by Dr. Shirley Strum

Opuntia stricta-like and Opuntia-dillenii-like plants have spread to Africa, Australia, and other parts of the globe. Many of them have become naturalized. The phenomenon is not an ancient fact; it is still happening. Each year new lands are colonized by Opuntia species of different types.

Dr. Strum (a professor at the University of California, San Diego) has been studying baboons in Kenya for some time. She reports that one Opuntia species has invaded one or two of her studies areas in the past years–she’s observed baboons eating the fruit (and elephants eating the fruit  too). Dr. Strum has studied how the Opuntia has spread, how animals interact with it. She reports that the plant has fruit much of the year, unlike other invasive Opuntia that seasonally bear fruit.

Her studies show us that desertification is a real problem around the world, and an ongoing problem. But, all is not bad. She reports that when the Opuntia invaded an area the people were able to make a juice that is served to tourists.

“When an invasive species of Opuntia cactus became a serious problem in the region (see History) UNBP helped the Twala women’s group develop a cocktail syrup from the fruit of the cactus, to market to tourists”

LINK:  Dr. Shirley Strum’s Web site (Uaso Ngiro Baboon Project in Kenya)

Opuntia that has invaded Dr. Strum's research areas, photo by Dr. Shirley Strum

North of Las Lajas, Nequen, Argentina

The southern part of Argentina is home to varieity of cacti, including opuntiads. Pterocactus, Austrocylindropuntia, and Maihueniopsis are all former members of the genus Opuntia. One nice Web site that shows plants and habitat photos is “Cacti from Neuquén, Argentina.”

The site discusses the plants that occur in the area, as well as the habitats that they are found in. The photos are not large but they are beautiful.

Tortoise on Pinzon Island, click image to read original article at the Skeptic

The Galapagos islands are the home of some very large Opuntia species. These plants serve at important sources of food for tortoises, terrestrial iguanas, cactus finches, and multiple insects.

It has been speculated that some of the tall tree-like Opuntia might have more bushy shapes but that they are pruned into tree shapes by turtles nibbling on lower branches. If such is the case, then it is expect that the lower, bushier Opuntia grow in areas that tortoises can’t reach. The Skeptic reports:

“As a result of natural selection on islands in the Galápagos where tortoises are found, Opuntia have evolved into tree forms, reaching a height of 12 meters. On islands where tortoises have never been present, Opuntia form clumps along the ground, reaching a maximum height of only 2 meters.”

The Galapogos Islands served as a laboratory of Charles Darwin who developed many of his ideas on speciation and evolution after studying the flora and fauna of the islands for many years. He took a trip around much of the world on the HMS Beagle (s ship of the British Royal Navy). His travels on the Beagle lasted nearly 6 years, with much time spent in South America including the Galapagos. He traveled to Australia and Africa as well.

Opuntia echios var. zacana, image from Wikimedia

Prickly pear is one of the common names for Opuntia, especially when referring to the fruits, which are indeed prickly with glochids. Many animals and birds have been observed eating prickly pears, and undoutedly these assist in disseminating the Opuntia seeds.

Red prickly pears in South Africa, click image for original blog article

South Africa has been the home of Opuntia (several types) for hundreds of years. The plants were introduced for fruit, or for cochineal production, as fodder for animals, or perhaps to provide a green vegetable to prevent scurvy in sailors. Opuntia have been the subject of various agricultural or popular publications.

Fluffy white cochineal insect on Opuntia, in South Africa, click image to see original blog and photo

The cochineal insect (Dactylopius opuntiae) has a long history in the New World; it was used by Native Americans to make a red dye (the insects a squashed and release a bright red pigment). Eventually, the insect spread to Africa, Asia, and Australia–just about where ever Opuntia species became naturalized. 

In South Africa the cochineal insect is used as a form of biological control, and it has been helpful (see abstract)  in reducing the numbers of unwanted Opuntia plants throughout much of the country.

The image in this post came from an Opuntia in South Africa. Click on the image to read the original post.

Lemur catta in Opuntia, click image for original article by Lisa Kelly

It seems that crows and baboons are not the only animals that eat the fruits of Opuntia introduced into Africa. In a Web article from Lisa Kelly (Washington University at St. Louis) it is reported that Lemurs (Lemur catta) eat the fruits of O. ficus-indica and O. stricta).

This might be important in Madagascar where much of the native habitat has been destroyed. It may be that some Lemurs can derive some benefit from introduced species of plants.

“In the extreme south of Madagascar, Lemur catta regularly utilize the introduced cactus species, Opuntia ficus indica and Opuntia stricta. This finding is significant as the habitat of this region, which is comprised of these cactus species as well as xerophytic Didiereaceae-Euphorbiaceae forest , represents over 90% of this species’ potential range. Moreover, the use of cacti as a primary ecotone for a primate species has never before been documented.”

Folks who sell things always have to market; there is a “Christmas” cactus, and an “Easter” cactus, and I wondered if there as such a thing as a “Thanksgiving” cactus. Thanksgiving is coming up in a week or two.

Thanksgiving cactus, image from Wikipedia

I Googled “thanksgiving cactus” and was only mildly surprised to find that there is indeed such a thing as a Thanksgiving cactus. And it blooms about a month or two before Christmas. S. truncata is related to the “real” Christmas cactus, which I guess is a hybrid of S. truncata and something else. The two plants resemble each other, but of course the Thanksgiving cactus blooms earlier in the year.

S. truncata is a native of Brazil where is typically grows as an epiphyte. It is one of those plants that just might make a great houseplant–not needing too much water, tolerating dry air, and not needing great amounts of light. I’m only guessing, but if the two plants depend upon long nights to bloom, it would seem that the Christmas cactus needs slightly longer nights than the Thanksgiving cactus.

Schlumbergera used to be called Zygocactus, and it has been cultivated for 100-200 years (hybridized too). It may be that there is no true S. truncata out there in floritsts’ shops–perhaps all the holiday cacti for Fall are hybrids. Who knows!

Opuntia anacantha, Argentina, photo by Willy Smith 2009

I had never heard of Opuntia anacantha before Willy Smith sent me a photo. Then I looked up the plant and the image is almost exactly as in Volume 1 of the Cactaceae by Britton and Rose (1919) on page 110.

Opuntia anacantha, The Cactaceae, Vol 1, Britton and Rose, page 110

Opuntia can be very difficult to identify, but in this case there seems to be no mistaking the linear cladodes with the fruits clustered along the distal half of the pad.  

The Britton and Rose volumes are truly amazing.

I don’t know the growth conditions for most of the South American opuntiads. I’ll just assume they don’t like too much water, and tolerate a bit of cold, unless I find out differently.

An email contact wrote to me that Opuntia humifusa can be found at various places on the Atlantic Coast of Delaware; it sounds like I need to make a road trip. The only problem is that it is mid-November and decidedly cool. I don’t think there are too many good day-trip days left in 2009.

Maybe I’ll be able to report next week that I found Opuntia in Delaware!

Opuntia humifusa flower, unusual with a bit of red in the center, photo by Dave Ferguson

Willy Smith’s Web site is unassuming if you happen in via the front page. But don’t let that fool you, Willy has a wealth of information in images and location maps. The power of his Web site will keep you coming back to view images of plants.  He has habitat shots, as well as photos of his hobby plants. 

 Willy provides habitat images of seven different genera in the Opuntiodeae: Austrocylindropuntia, Opuntia, Pereskiopsis, Pterocactus, Tephrocactus, Maihueniopsis, and Tunilla.

 Willy provides nice field images of multiple Opuntia species of his country (Argentina). These are Opuntia anacantha,O. cordobensis,O. cardiosperma,O. elata,O. paraguayensis,O. penicilligra,O. quimilo,O. salmiana,O. schickendantzii,and O. sulphurea.

 In addition to loving cacti and helping us by providing information and photos, Willy organizes cactus tours of his part of the world. Check out his tour page below if you want to know more. 

• Link: Argentine Cacti
• Link: Cactus Tours