Opuntia fragilis

[Weiser]

 The hardiest of the hardiest, and the most widely distributed of the Opuntias. Found growing in portions of 22 States, and 5 Canadian Provinces. This small mounding Opuntia is the most cold tolerant cactus in North America. It can be found growing almost to the Arctic Circle in Alberta and British Columbia.
 As the scientific (Opuntia fragilis) and common names (brittle prickly pear) imply, the pads detach easily at the slightest touch. This allows it to vegetatively propagate itself.
 There are several isolated populations in the upper mid western states (IA, IL, MN, WI, MI,) that rarely flower. It is believed that these populations use this vegetative method almost exclusively to perpetuate themselves. It has been speculated that Native American traders, or animals may have inadvertently spread it's range eastward, by pads attached to their trappings, furs or hides. There are on going studies of these populations. Here are links to some of the on going studies by Dr. Eric Ribbens concerning these eastern populations.
http://www.wiu.edu/users/mfer1/research/opuntia.htm
http://www.wiu.edu/users/mfer1/research/Opuntia_fragilis/index.htm
http://opuntiads.com/zpdf/opuntia-fragilis-iowa.pdf
http://opuntiads.com/zpdf/opuntia-fragilis-michigan.pdf
http://opuntiads.com/zpdf/opuntia-fragilis-illinois.pdf
 The populations found further west tend to flower more, utilizing both floral and vegetative strategies to colonise and reproduce. O. fragilis is known to hybridize with other Opuntias frequently, especially O. Polyacantha. Many natural hybrids are found where it's habitat overlaps with other Opuntias.  
 There is a fair amount of diversity through out it's natural range. Most noticeable in the shape of the pads and length of the spines. The pads may be oval and plump (egg shaped)or flat, oval shaped pads. The spines can be non nonexistent to twice the length of the pads, coloration ranges from white through red/brown, The flower coloration is always yellow and may sport red filaments. I have heard and seen what are reputed to be pink flowered forms but, I have to agree with the prevailing opinion that, they are of hybrid origin.
There are some who say O. fragilis dose not bloom well for them. I find that the western forms if  allowed to chain the pads, two to three long, will set flowers consistently. You want to give it enough moisture to fill out the pads, and plenty of full sun. I recommend a well drained planting medium. It however is known to grow along the British Colombian coast and in wetter micro climates of the Midwestern states, rooted into moss covered, rock crevices and depressions.
 Here is an extensive  monograph about Opuntia fragilis authored by Dr. Eric Gibbens and published in the Haseltonia 14: 94–110. 2007.
http://opuntiads.com/zpdf/opuntia-fragilis-haseltonia.pdf
 Since this species stays low and mounds, I use it in my garden extensively, with eight clones spread through out the garden. I place it back out of the way to avoid disturbance from pets or passers by.
 Now for a few shots.

[Lori S.]

Superb essay, John!
I'm afraid I am one of those for whom it will not bloom... in its current conditions, anyway.  I saw a nice specimen on the weekend (on a tour of the fascinating garden of a local botanist) that will soon be covered with blossoms.  I'm deeply envious!!

It can be found growing almost to the Arctic Circle in Alberta and British Columbia.

PS.  Please forgive me, but for the sake of the fragile, winter-worn psyches of Canadians who sometimes wonder if it is indeed creeping closer (case in point, the snowfall here 2 weekends ago), I must point out that the Arctic Circle is still another 450 miles or so north of the northern borders of Alberta and British Columbia.    Don't want mass suicides breaking out at the suggestion that the Arctic Circle has been creeping closer!  

Terrific photos!  I look forward to seeing this species in bloom when we head out to the Red Deer River badlands in summer!

Edit:  Here is a range map for O. fragilis (N.B. not a plant of the boreal forest nor of the arctic tundra...):
http://www.efloras.org/object_page.aspx?object_id=13216&flora_id=1

[Weiser]

Please forgive me, but for the sake of the fragile, winter-worn psyches of Canadians who sometimes wonder if it is indeed creeping closer (case in point, the snowfall here 2 weekends ago), I must point out that the Arctic Circle is still another 450 miles north or so of the northern borders of Alberta and British Columbia.       Don't want mass suicides breaking out at the news!    

No please forgive me. I guess I went for a little too much dramatic effect!  :

[RickR]

I've seen Opuntia fragilis in many places throughout Minnesota (not the ones at the Northwest Angle though), and none of them are as garden worth as your clones depicted here.  Very nice!

[James R.]

Lichen has been shown to have some affect on whether some varieties of O. fragilis will flower or not. I have 8 different var. from various collection locales in Utah and some are shy to flower while others grow two sets of pads and flower twice in the summer. The shy flowering ones generally are thought to have a symbiotic relationship with lichen growing on the soil and on surrounding rocks. If some of the plants do not have this they are believed too rarely if ever flower in cultivation. I grow my shy flowering ones close to rocks covered in lichen in hopes that they will be able to develop this relationship but my rocks are from California and the plants Utah so I don’t expect miracles but there is always hope. My favorite one is O. fragilis forma denudate nearly round pads with almost no spines and a purple hue.   

[Weiser]

I have not heard of this symbiotic relationship before. Interesting. I just grow mine on DG with plenty of heat, sun and consistant moderate moisture.  They seem to appreciate this treatment.  All of my clones flower every year.

[James R.]

I have done a lot of research on this species and I personally think that it needs to be broken up into different species or subspecies rather than just one. There are so many different forms it is like calling every plant that looks similar the same name. I have two different clones that will not bloom but they bloom great in the wild in Utah likewise they will not bloom in cultivation in Utah in their native soil, "so I know its not just me".
   The desert crusts have a biodiversity that we have barely even started to look at. It is a nitrogen fixer and does so many other things that are now starting to be addressed. In certain deserts that have lots of introduced grazing farm animals trampling the native crust the areas are turning into sand dunes since the soil is not protected from the extreme weathering. I love how interconnected the world is, "we are but one organism living in perfect harmony".

[Weiser]

I have read about biological soil crusts. They are indeed an integral and major component of the undisturbed desert landscape.  I must say that I had never heard of this specific interrelationship until now. I find it very interesting. Thank you for the information.
Here are a few sights and pdfs that give an overview of soil crusts for those with an interest.
http://www.soilcrust.org/crust101.htm
http://www.mineralarts.com/artwork/cryptos.html
http://www.blm.gov/nstc/library/pdf/CrustManual.pdf
http://www.fs.fed.us/rm/pubs/rmrs_p031/rmrs_p031_074_076.pdf
http://ftp://ftp-fc.sc.egov.usda.gov/GLTI/technical/publications/micro-crusts.pdf
http://conservancy.umn.edu/bitstream/60123/1/7.2.Kettenring.pdf
  

[McDonough]

I have not heard of this symbiotic relationship before. Interesting. I just grow mine on DG with plenty of heat, sun and consistant moderate moisture.  They seem to appreciate this treatment.  All of my clones flower every year.

John, what is DG? An acronym for something?

[Weiser]

It's disintegrated granite. Locally common soil deposits made of weathered crumbled granite particles. It can be a mix of varying sized pieces from 1/2 inch and down. I buy 1/8 inch and down as a planting medium. Many of the golden soils seen on western mountain slopes and screes are composed of this matrix.  It has excellent sharp drainage properties and just enough fines to stay damp.

[McDonough]

It's disintegrated granite. Locally common soil deposits made of weathered crumbled granite particles. It can be a mix of varying sized pieces from 1/2 inch and down. I buy 1/8 inch and down as a planting medium. Many of the golden soils seen on western mountain slopes and screes are composed of this matrix.  It has excellent sharp drainage properties and just enough fines to stay damp.

Thanks John, DG sounds like good stuff.  I don't know of any such material available here, but then again, I haven't really looked.

[Weiser]

James
I correspond occasionally with a DR. Eric Ribbons about Opuntia fragilis. He is an Associate Professor of Biology at Western Illinois University.
Dr Ribbons has been doing research and studies on Midwestern populations of O. fragilis many of which are, as you say are "shy to flower".
Dr. Ribbons web sight has some good information about the species.
http://www.wiu.edu/users/mfer1/research/Opuntia/opuntia.htm

He also authored an article about of the species for the Haseltonia publication in 2007
http://opuntiads.com/zpdf/opuntia-fragilis-haseltonia.pdf

You will find this article and several others Authored By Dr. Ribbons at this sight.
http://opuntiads.com/html/opuntia-fragilis.html


http://opuntiads.com/zpdf/opuntia-fragilis-iowa.pdf
http://opuntiads.com/zpdf/opuntia-fragilis-michigan.pdf
http://opuntiads.com/zpdf/opuntia-fragilis-illinois.pdf
 
 
 
 

[James R.]

Thank you for the links.
 I was only able to read the first one as of yet, however; I do find the information very interesting. I found the part about the Lichen possibly facilitating flowering by cooling the soil interesting. I feel that the added nitrogen being fixed from the Lichen plays an integral part as well and I agree it holds moisture in the soil.


Here is one of my favorite varieties of Opuntia fragilis var. denudata from Utah. 

[McDonough]

John, those are excellent links for Opuntiaphiles (Opuntiads.com), what a fantastic reource, must admit to spending lots of time looking around the galleries and reading up on O. fragilis, I had no idea about its surprising northerly range.

James, what a cute rolly-polly thing Opuntia fragilis var. denudata is, I like it!

[RickR]

James, what a cute rolly-polly thing Opuntia fragilis var. denudata is, I like it!

I was almost surprised, Mark, with your "no thorns" rule...but then I see that this one has no thorns!  (and indeed, cute)

There are, apparently, certain O. humifusa that are thornless, or nearly so.  I was hoping the Minnesota provenance ones would be such, but not so.