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A Primer on Washington Native Cacti

Introduction

To most people, Washington is a state more likely to be associated with dark, looming evergreen trees and perpetual clouds and mist than it is with cacti. But those of us who live in this wonderful state know that it offers a great diversity of ecosystems and climates, from rolling prairies to temperate rainforests to rocky alpine regions. There are also the deserts, which occur wherever mountains block enough of the precipitation to support such an ecosystem, including a large area of Eastern Washington. Much of Washington's desert has been converted to cropland, ranches, orchards and vineyards; but some remains untouched, and in such places cacti can be found. Perhaps more surprisingly, a few areas of western Washington are dry enough to support native cacti! Even the most seasoned Northwest gardeners probably don't associate cacti with the native plants of western Washington - yet one species, Opuntia fragilis, finds its home here.

While Washington doesn't have the same diversity of cacti as, say, the Southwest; Washington's cacti are intriguing for another reason: few botanists have studied them very thoroughly, and much about them remains quite mysterious. Because of this, their taxonomy is rather confused, and sometimes 'forms' of cacti can be found that don't clearly belong to one of the documented species. Even more interesting, cactus populations seem to appear and fade out in various places, or change in their morphology, over periods of time. The reasons for this are not well known.

So, what follows is a summary of all the cacti known to be native to Washington: officially, four species belonging to two genera, but practically, not quite that simple!

Opuntia

Opuntia is one of the world's largest genera of cacti, and is the primary representative of one of three subfamilies within the cactus family. It includes the familiar prickly-pear, with their rounded, spiny pads, and cholla of the Southwest US. Most species produce showy flowers which may be pink, yellow, red, orange, and occasionally purple or white depending on the species and where it was collected. Opuntia species are found throughout North America - in fact, wild plants of some Opuntia species have been documented from every US state except five: Alaska, Hawaii, Maine, New Hampshire, and Vermont. While many species of Opuntia can be found in the southwest and Texas, only three species are native to Washington: however, these three species include a number of interesting forms.

Opuntia fragilis - Brittle Prickly Pear

To those familiar with the large, shrub-like prickly pears of Arizona, Opuntia fragilis would hardly be recognized as a close relative of those impressive plants, but indeed it is! However, it has much smaller pads than most Opuntia species, usually just 1 - 2" long or occasionally a little longer. The pads are "fat" and can be cylindrical to slightly flattened in shape. Some older references state that the pads are invariably cylindrical, but a thorough inspection of a sample of wild O. fragilis plants will reveal that this definition is too narrow. The pads have spines that may be rather soft and white to more rigid and somewhat golden or brownish in color. The spine color also varies according to the time of year. In June, yellow flowers are produced, but some forms of this species are rather shy to flower.

The names "fragilis" and "Brittle Prickly Pear" are assigned to this plant for a reason; that is, the pad joints are very brittle and apt to break with very little force. With this in mind, and also considering the pads are so small, the plant is seldom able to grow taller than about 6". Most frequently, it forms broad, low mats on sunny, dry south or southwest facing slopes with gravelly or sandy soil. It is at its best in isolated areas where competition from other plants is minimal.

Opuntia fragilis is distributed widely throughout North America, including some locales in the Midwest and Southwest. It is the only cactus species native to western Washington. Here it is found only within the Olympic Rainshadow, especially in the San Juan Islands. It is also known from one site on Whidbey Island, a very few scattered locations north and east of Sequim, and near Port Townsend, though it has become very difficult to find on the Olympic Peninsula. In British Columbia, similar populations are found in the Gulf Islands in the Strait of Georgia.

In Eastern Washington, the most extensive Opuntia fragilis populations are found in the lower hills and plateaus surrounding the Okanogan River Valley in north central Washington, and extending occasionally to the east of this region into Ferry County. These plants, which I call the Okanogan form of O. fragilis, generally have rounded pads forming large mounds, and reddish-brown spines. The locals there complain that the brittle pads break off and bother their horses when they are riding trails through the foothills. This Okanogan form also grows on the Canadian side of the border, where it feels very insulted if you don't spell it the Okanagan form.

Elsewhere in eastern Washington, O. fragilis is rare. It has been documented from the Yakima River Valley, but these references may actually refer to O. columbiana or other Opuntia forms that do not quite fit the parameters for O. fragilis. It has also been recorded in Klickitat County along the Columbia River, where a variety of Opuntia forms mostly looking like O. columbiana can be found, but with some O. fragilis and rarely O. polyacantha as well. The scarcity of this species throughout Eastern Washington is surprising given the availability of suitable habitat on many of the hills and rocky coulees.

In addition to the western Washington form and the Okanogan form, a couple other obscure cacti resembling O. fragilis should be mentioned. The first is an interesting plant that is found just south of Wenatchee. Generally resembling O. fragilis, it differs in having pads that are much larger, almost resembling one of the South American Tephrocacti. However, the pads are brittle like O. fragilis, and the yellow flowers are similar. It has been sold incorrectly as O. columbiana by some nurseries, and has also been called "Opuntia fragilis hybrid." Roughly similar plants have also been found in central Oregon. Another interesting plant can be found near Keremeos, BC, a form with very long, dense orange-black spines that grows into great mounds. While I've never heard of anything like this growing in Washington, I have to mention it since it is so distinctive and could make an excellent ornamental plant.

The brittle joints of this species are an obvious reason it has been such a successful colonizer of so many places in the Midwest and West. Pads are easily picked up by medium to large mammals including deer, elk and otters, and carried off to other locations where they root and grow into new plants. The pads are also capable of surviving several days floating on salt water (Domico). Some have postulated that this species seldom or never perpetuates itself through sexual reproduction, since vegetative propagation is so successful for it. However, the genetic variability in spine color, pad shape, etc. within a given O. fragilis population, especially in western Washington, tells me that some reproduction from seed is occurring as well. Also, I have found a couple small plants in the Sequim area that are clearly seedlings.

Opuntia columbiana

If O. fragilis is so small it hardly looks like a prickly pear, O. columbiana is quite a bit more conspicuous and immediately says "cactus" to anyone who encounters it. Unlike O. fragilis, it is not native to a large area of the continent - in fact, it is known only from Eastern Washington, northeast Oregon, and a small area of western Idaho. Having larger pads commonly 3 - 5" long and yellow flowers, it often forms large mats on sunny south-facing slopes.

Quite a lot of taxanomic confusion surrounds this species. Some books refer to it as Opuntia x columbiana, indicating that it is a hybrid between O. fragilis and O. polyacantha. I find no reason to suppose this is true, but there are some cactus populations I would like to see before drawing my conclusions. For example, the plants along the Columbia River are said to represent a variety of forms ranging from fragilis-like small pads on up to large padded polyacantha-like plants. Another reason this theory seems doubtful is that there are many places throughout the Midwest and West where O. fragilis and O. polyacantha occur together. Therefore, plants resembling O. columbiana should thus be expected to be equally widespread, but they are not. Some references refer to this plant as O. erinacea var. columbiana. This classification is plausible since the relation between O. erinacea and O. columbiana seems close indeed. However, considering one as a subspecies of the other still seems unnecessary; since the resemblance between these two plants is not that much more obvious than, for example, the resemblance of O. columbiana to certain O. polyacantha forms; and because there is such a large distance between wild populations of both: other forms of O. erinacea are found far away in southern Utah, southern Nevada and northern Arizona.

Additionally, there is a surprising range of variation in the plants that are classified as O. columbiana, not only among different populations in different areas, but even from one plant to the next in a single population. The best example of this is in Whitman County, Washington, where extensive populations can be found growing on the cliffs and rocky slopes above the Snake River northwest of Clarkston, where their straw-colored spines blend in with the grass. Some plants have long pads with white spines, some plants have rounded pads with golden spines, and some have small pads with much more closely set, very long spines. Crested forms can occasionally be found as well. These plants resemble O. polyacantha quite a bit, but the pads are narrower and smaller than typical O. polyacantha. The only flower color I have seen on these plants is yellow, but I wouldn't be surprised to find an occasional pink one someday. Going farther south from there into Asotin County, one starts to find plants that look more like O. polyacantha, which I will discuss below. O. columbiana has also been recorded from along the Snake River southeast from Clarkston (though these references may also refer to more polyacantha-like plants - I haven't seen them), and along both sides of the Columbia River near Wishram and Maryhill, and especially on Miller Island. It might possibly also be found on the Hanford Nuclear Reservation.

A different form of O. columbiana occurs in the Yakima Valley. I haven't seen very much of this form but I know that it has smaller pads than the Whitman County form, and, in some cases, fewer, thicker spines. This cactus differs from Opuntia fragilis in its preference for heavier, basaltic soils which are often clay-like in consistency (Dringman). For this reason alone it should perhaps be given subspecies or at least varietal status by taxonomists. This form is said to have been quite prevalent at one time in the Yakima Valley, growing on sunny slopes and near the riverbeds under the cottonwoods. These plants are also said to occur in the Yakima River Canyon and are quite common there according to some reports, though I have never found them there myself. They may also occur, though rarely, along the Columbia River around Vantage: I found just one single plant there once, but I have heard rumors of more.

One more interesting plant should be mentioned: an odd creature that would probably be quickly lumped into O. columbiana by most, but I think it deserves more attention. Growing at the confluence of the Naches and Tieton Rivers in the eastern foothills of the Cascades, this diminutive cactus has small pads on rather small plants, but very long, white spines, up to 2" long and frequently longer than the pads. The flowers are quite large too, and they may be yellow or pink! While the plants look more like O. columbiana than anything else, surprisingly, the joints are extremely brittle like those of O. fragilis. Does this suggest some kind of genetic link between O. columbiana and O. fragilis? Or should these plants be regarded as another unique O. fragilis form masquerading as O. columbiana? It should also be noted that they grow at the bottom of the valley by the river in gravel, rather than on the clay basalts of the hillsides: so far, I know them only from the river bed, but I should explore that area further.

Opuntia polyacantha

"Polyacantha" meaning "many spines" is an accurate description of this widespread prickly pear species. Like O. fragilis, its distribution extends all across the West, south to Mexico and north into Canada. It has the distinction of claiming the most northerly natural occurrence of any cactus in the world: amazingly, it ranges just barely into the Northwest Territories, Canada. Innumerable forms of this species can be found all across the west, including small pads, large pads, long spines, short spines, and flower colors including yellow, purple, pink, and rarely orange or white. A typical plant will have pads in the neighborhood of 5 to 6" long and slightly narrower, with many white spines, on an attractive low plant that either creeps along the ground or grows semi-upright to about 1'. It is quite a tough plant and most definitely not brittle to the touch like O. fragilis.

Although most references acknowledge the occurrence of O. polyacantha in Washington, it is actually quite rare here and some have even doubted its existence in our state. It has been recorded from along the Columbia River near Wishram and Maryhill, but it is far from common: quite possibly, those plants got there by being washed downriver from the Hells Canyon area (where it is common) before the dams were built.

Certainly, however, Asotin County is home to some populations of O. polyacantha, especially as you drive south and west from Asotin. These plants are rather similar to the Whitman County O. columbiana forms, but I think they are distinct enough since they are smaller plants with larger pads and a more polyacantha-like creeping habit, as opposed to the large mats of O. columbiana along the Snake River. Probably these plants represent an intermediate form between Whitman County O. columbiana and Wallowa County (Oregon) O. polyacantha, but to my eye they fall within the parameters for O. polyacantha. I don't doubt that many more of these cacti can be found along the remote cliffs and canyons of southern Asotin County.

Rumors have also circulated that a different form of O. polyacantha may occur along the valley floors in the northeast corner of Washington. This would seem quite unlikely, except for the known occurrence of some polyacantha-like cactus near Cranbrook, British Columbia, which isn't too far away.

Speaking of British Columbia, our neighbors to the north possess some very interesting plants that present problems with defining O. polyacantha. While botanists have regarded O. polyacantha as being native to BC, what passes for this species there is not the same as O. polyacantha in much of the west. These variable plants, which are especially common around Ashcroft, Cache Creek, and Lillooet, have very flat pads that are always smaller than most "normal" polyacantha - about 2 - 3" inches is common. Some of them are fascinating plants resembling miniatures of O. phaecantha with fiery spines, or sprawling plants with hundreds of congested pads - often with very different looking plants found together in mixed populations. Additionally, these plants are not tough like O. polyacantha, but brittle like O. fragilis, severing readily with very little force. Their distribution in a previously glaciated area also suggests that they wouldn't be there had they not been brittle enough to be carried there from somewhere warmer. However, as no such plants are found outside of British Columbia, their ultimate origin remains a mystery.

Pediocactus

The genus Pediocactus is a much smaller group of cacti than the Opuntias, and they belong to a different subfamily within the cactus family. They are found throughout the mountainous regions of the West, generally occupying remote and inaccessible areas of high desert or drier mountain ranges, often at very high altitudes. Some of them are low, small, solitary plants; others form impressive mounds. All are very showy plants in flower; the flowers may be white, pink, or salmon in various shades, depending on the species. In Washington, we have only one native Pediocactus species.

Pediocactus nigrispinus - Hedgehog Cactus

In Washington, Pediocactus reaches its northernmost and westernmost distribution, as well as growing at a lower altitude than anywhere else in the west. The species we have is Pediocactus nigrispinus, though many references continue to list it as P. simpsonii. It is quite distinct from P. simpsonii, however, having larger bodies with black spines, and usually pink flowers. On some plants, the spines can also be grey or golden. Some plants are solitary, but others may have as many as 30 offsets or more, and form large mounds to 1' or higher, and 2' across. Individual bodies may range in size from about 2 - 8" tall and 3 - 6" across. It is frequently an impressive plant that looks more like it belongs in Arizona than western Washington. The flowers are showy as well - often 4 - 8 buds at the top of each stem will open into beautiful deep pink flowers, which are large enough to be seen from a great distance. Occasionally peach colored flowers can be found as well. Flowering usually occurs around the beginning of May, and seeds are ripe in June, though this can vary substantially depending on the weather.

Despite some degree of variability, Washington's Pediocactus populations all clearly belong to one species, P. nigrispinus. Older references may call it P. simpsonii var. robustior, but this name is now applied to another Pediocactus not found in Washington. There are many forms of Pediocactus found throughout Oregon and Idaho and other parts of the West that were at one time a taxonomic mess. These have largely been sorted out by botanists, with varietal status having been given to some populations. I hope someone will do the same with our native Opuntias!

Pediocactus used to be easy to find near Vantage in central Washington, but now most easily accessible populations have been wiped out from over-collecting of the plants. Numerous populations remain, however, in less accessible areas on both sides of the Columbia River, frequently on rocky outcrops high above the river or on remote gravelly hillsides and boulder fields out of the river's view. In the Colockum Wildlife Area, some populations can be found as high as 3,500' (possibly 4,200'?), its highest known occurrence in Washington. Pediocactus has also been found in a few isolated sites around Ellensburg and Yakima. As it occurs along the Snake River near Imnaha, Oregon, it is not out of the question that it may be found in the extreme southeast corner of our state, along the Grande Ronde River or near the confluence of this river and the Snake; however, it has never been reported from this area that I know of. There are reports of Pediocactus occurring in southern British Columbia, but I consider these to be questionable at this time (though I would love to be proven wrong!). Most believe this possibility to be very unlikely since it would be difficult for Pediocactus to re-colonize an area that had been covered in glacial ice thousands of feet deep during the ice ages (recall the discussion about the means by which Opuntia fragilis is distributed, an advantage not available to Pediocactus).

Escobaria vivipara

A low-growing, mounding cactus often forming many offsets, this pink-flowered species is native to many areas throughout the West, and exhibits great variation in spine color and plant size. It is not commonly believed to be native to Washington, but it is certainly native to western Idaho and it can also be found as far north as Alberta, Canada. It should be mentioned because a single plant of it was once found among a Pediocactus population near Soap Lake. However, no more specimens have been located in this area. It has also been reported from Wallowa County, Oregon (though it is rare there), which suggests that the possibility of finding it just on the Washington side along the Grande Ronde River, though unlikely, cannot be ruled out.

Growing Washington's Native Cacti

All of the above cacti make excellent and rewarding ornamental plants. Even those that look rather small and uninteresting in the wild can make excellent focal plants in the rock garden or xeric bed. In western Washington, all will require the exceptionally well drained soil found in a rock garden or cactus garden. You can mound up a soil mix composed mostly of grit, pumice or sand and you should have excellent results. They can also be planted between cracks in rocks. Any situation where moisture will drain away quickly, or where the roots are protected from rainfall will work for them. Opuntia fragilis prefers rather sandy soil, but the others will thrive on coarse, gravelly soil without too much fine material. In Eastern Washington, all of these cacti can be grown on heavier soils, since they will experience much less precipitation. In areas receiving under 12" of annual precipitation, they can even be grown successfully on heavy clay. Cold-hardiness is unlikely to be a problem for our region: Pediocactus nigrispinus is hardy to at least -25°F, perhaps lower, if it is kept dry; and the Opuntias can tolerate occasional dips to -40°F and seasonal snow cover.

The Opuntias are generally easiest of our native cacti to grow, and will root easily from pads collected in the spring. O. fragilis and its hybrids will tolerate a little more moisture than the other species mentioned here. Pediocactus nigrispinus has a reputation for being difficult in cultivation outside its native habitat. I haven't heard of a lot of people attempting it in western Washington, and it has never been common. I think it could be grown in drier areas of the Puget Sound region, but it would probably be exacting in its requirements for soil drainage, and would benefit from being sited in a rain protected spot such as under the eaves of a house. Pediocactus nigrispinus may also require a high soil pH to perform well (Dringman), something that can be difficult to accommodate in western Washington. Compared to Pediocactus, Escobaria vivipara is a very easy cactus to grow and will tolerate both cold and moisture with ease.

Save The Cacti!

Washington's cacti, unfortunately, are in peril. There seem to be two main threats to their future survival in the wild: the expansion of agriculture, and the invasion of non-native European grasses from Europe that have been here since about the turn of the century. This appears to be true on both east and west sides of the state. Opuntia fragilis was once much more common in the Sequim area, but can now it be found only in a very few isolated patches. Of course, much of the area has now been developed for agriculture. It is also disappearing from the San Juan Islands, and has disappeared completely from some locations including, ironically, the Cactus Islands (Domico 1999). A noted increase in summer precipitation, which encourages more vigorous growth of the competing non-native grasses, has been postulated as a reason for the decrease in these populations (Domico 1999). Surprisingly, there seems to be little local interest in preserving these plants in the Sequim area, but much more in the San Juan Islands (Domico 1999).

Similarly, cacti are now absent from large areas of eastern Washington where they used to grow. Non-native grasses have out-competed the cacti for light and nutrients in many places. Lesser threats to their preservation include the expansion of suburban development, over-collection by irresponsible individuals, and sheer carelessness by property owners where cacti are found. Development has especially been a problem from Wenatchee north along the Columbia River, where O. fragilis used to be more abundant; and also east of Yakima where a population of Pediocactus faces an uncertain future. Over-collection has probably not affected Opuntia populations signigicantly, but Pediocactus has been collected to death in a few places that it used to grow in central Washington, such as along the Columbia River near the intersection of Interstate 90 with State Highway 26. Also, on more than one occasion, the Washington State Department of Transportation has been known to remove large Opuntia colonies from the sides of highways.

So, what to do?

First of all, if you have cacti on your property, make an effort to preserve them. If you hear about someone who is going to destroy their cacti to make way for development, or they simply don't care about them, encourage them not to. Failing that, salvage as many cacti as you can so that you can grow and preserve them. It's difficult to stop the invasion of non-native grasses and other invasive competing plants, but this may be worth attempting on a small scale in some situations.

Second, don't overcollect. Opuntias should not be collected as entire plants, but should be propagated only from cuttings (which is easily done) so that the original plant may remain in place. Of course, this should only be done in places where the collection of plant cuttings is legal to begin with. Serious collectors can also attempt to collect and grow seeds. Any collecting at all may soon become illegal for all populations of O. fragilis in Washington, if it's not already, as its conservation status is currently under review. Pediocactus plants should not be collected. Wild plants take many years to grow and are irreplaceable once an entire population has been wiped out. They should be grown from seed only, or purchased from reputable nurserymen.

Finally, spread the word! Encourage your garden buddies to grow cacti and pass along propagules to your friends, especially if they are at all interested in succulents or rock gardening. Those of you who are more involved in political, environmental or community affairs can do as much as possible to raise awareness and interest in preserving cacti within your respective spheres of influence. With a little effort on our part, we can hope that the unique cacti of Washington can remain for future generations to study, appreciate and enjoy.

Literature Cited and Endnotes

This information comes from a variety of sources, including:

Domico, Terry. Brittle Prickly-Pear Cactus (Opuntia fragilis) in the San Juan Islands and Puget Sound Region of Washington State. Douglasia Occasional Papers, Vol. 7, No, 1, pp. 37-50, 1999.

Dringman, Dixie A. Washington State Cacti and their History. Cactus & Co. publication, date unknown.

Dringman, Dixie A. Opuntia erinacea var. columbiana. British Cactus and Succulent Journal Vol. 15 (3), 1997.

Other indirect and personal sources also include Dixie Dringman (besides the above citation), Fritz Hochstaetter, Bill Beaston, Jay Akerley, Sean Hogan, Benny Møller Jensen, and the Burke Museum's Online WTU Herbarium Image Collection.

In the interest of protecting cacti from the wiles of unscrupulous collectors, a deliberate effort has been made in this article not to reveal the exact locations of vulnerable cactus populations with greater specificity than has previously been done by other readily available information sources.

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