Coconino Western OakQuercus x undulata 'Coconino'
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Quercus x undulata 'Coconino'
Outdoor Growing zone
Full Sun, Partial Sun
The Coconino Western Oak is a unique variety of the wavyleaf oak, a natural hybrid oak from Arizona. It has attractive silvery blue-green leaves with spiny edges, more like a holly than an oak tree. It forms a large shrub or small, multi-stem tree growing to perhaps 20 feet tall and 15 feet wide. It is completely evergreen even in cold zones and combines excellent drought resistance with cold resistance as well. Grow in a xeric or low-water garden, on dry, rocky slopes, as a specimen or screen.
Full sun or some partial shade are fine for the Coconino Western Oak. It grows in any well-drained soil, including rocky and alkaline soils, and once established it is very drought resistant. It isn’t bothered by pests or diseases and it is likely that deer won’t eat it either. You could do some formative pruning and make it more tree-like, if you wished, or simply leave it to take care of itself, even in harsh conditions.
Hiking the Grand Canyon is something supremely American, and an experience of the West that should be on everyone’s bucket list. Many will go for the views, but keen gardeners and nature lovers will go for the plants and animal life. Coconino County, Arizona is on the southern rim of the Canyon, and a popular starting point for hikers. Travel the trails and you can’t help but notice a shrubby tree with silvery-green leaves – thick and leathery that are perhaps more like a strange holly than an oak tree. But oak they are – not the majestic trees of the east and Europe, but adaptations for survival in hot arid conditions, but also for cold winters. When gardeners come to make xeric, or low-water gardens, often the choices of really drought-resistant plants are limited by climate, as many are only hardy in warmer zones. That’s one of the things that makes the Coconino Western Oak so special – its ability to tolerate the winters of zone 5 and probably colder, yet take scorching sun, heat and dry, dry soil. Even if it wasn’t strikingly beautiful in a rugged desperado kind of way, that would be enough to make it a valuable garden plant. So if you are looking for drought-tolerant shrubs that can take your cold winters too, then you have found a real treasure.
The Coconino Western Oak is a shrubby small tree that can in time reach 20 feet tall with a spread of 10 to 15 feet. With a little trimming it can be made into a multi-stem tree with a spreading, open crown, or kept more bushy and lower. The bark is gray-brown, darker on older branches, where it begins to split and flake into long strips in an attractive, rugged fashion. Younger stems are lighter pale brown, with a slightly ‘fuzzy’ texture. The leaves are small, no more than 2 ½ inches long, and mostly smaller. They are oval and leathery, with 5 to 7 spine-tipped lobes along each edge, and a pale-brown central vein. The color is a silvery blue-green, with a matt, slightly rough texture and a furry underside. All these are adaptations to conserve water and prevent being eaten. Trees will reveal their oak nature by producing small acorns, only ½ inch long, with a small, scaly cup holding their base. This tree has proven to be fully evergreen wherever it can be grown.
This is a perfect choice for a water-wise garden anywhere in the country, including difficult areas in the west, with extreme dryness and heat. Grow it as a specimen tree, or keep it more shrubby at the back of a bed. Plant it on a rocky slope, or plant a row as a tough and reliable screen. Or, simply plant it for its unique character as an interesting plant, perhaps behind a rock garden.
The Coconino Western Oak is hardy at least through zone 5, and probably in zone 4 as well. It grows in all warmer zones as well, more adapted to dry summers than wet, humid ones.
Sun, sun and more sun are just fine with the Coconino Western Oak, but it will also grow in partial shade beneath larger trees. Too much shade, though, will probably make it spindly and greener, spoiling its best features. Plant it in any well-drained soil, including rocky ground and limestone soils.
Probably untouched by deer, and seemingly not bothered by pests or diseases, all you need to do with your Coconino Western Oak is to water it while newly planted. Once established it will take care of itself. You could do some formative pruning when young, shortening back long stems to encourage a more bushy habit, or raising up the crown to show off the attractive bark, but these are all personal choices – not essential.
In the west there are several species of oak trees that have been described, with Quercus gambelii a key species. It is a variable tree, from shrub to 100 foot specimen, depending on the location. The leaves are deeply-lobed in a typical ‘oaky’ kind of way. Other species occur alongside it and in surrounding areas seem to hybridize with it, creating a complex situation for botanists. Plants like Q. arizonica and Q. turbinella are common partners, among others, in this crossing, but distinguishing which cross is which for a specific plant is virtually impossible – a botanist’s nightmare. So all these ‘hybrid swarm’ species are called Quercus x undulata, the wavyleaf oak, or sometimes Quercus x pauciloba. Mark & Jolly Krautmann own Heritage Seedlings and Liners, a specialist propagation nursery in Salem, Oregon and are renowned for their ability to propagate difficult plants. We don’t know for sure, but it looks like they were hiking the Mogollon Rim of the Grand Canyon in northern Arizona – Coconino County – and found an interesting example of the wavyleaf oak. They named it Coconino and offer it with the trademark name of Western Oak™, to distinguish it from other, less interesting varieties of this natural oak hybrid.
We love being able to offer you unique and fascinating plants – and the Coconino Western Oak is certainly that, as well as being a terrific xeric or low-water garden plant that is also very cold resistant. We don’t have plants like this in stock very often, and they don’t stay long, so order now and grow a piece of Arizona in your yard.