water-wise gardening

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Drought Tolerant Plants: Blue Flax

“Lewis’s prairie flax is a pretty garden ornamental suited to hot, dry sites. Each morning delicate sky blue flowers open on slender arching stems, only to fall off in the afternoon and be replaced by others the next morning. In spite of its fragile appearance, it is quite sturdy and may put out a second flush of blossoms on new growth in late summer.” — Common to the This Country: Botanical Discoveries of Lewis and Clark by Susan H. Munger

When selecting plants for a waterwise garden, it is imperative that at least a portion of the plants are easy to grow and maintain and are adapted to a wide variety of conditions. This will ensure a more successful garden, both functionally and aesthetically. Luckily, there are a number of drought-tolerant plants that pretty much anyone can grow without too much trouble. Blue flax, in my opinion, is one such plant.

You may be familiar with flax as a culinary plant, known for its edible seeds which are used to make flour (i.e. meal) and oil. Or perhaps you’ve used linseed oil, a product of flax seeds, to protect wooden, outdoor furniture or in other wood finishing projects. You may also think of linen when you think of flax; and you should, because linen is a textile made from the fibrous stems of the flax plant. All of these products generally come from a domesticated, annual flax known as Linum usitatissimum – a species that has been of benefit to humans for millenia. Various species of flax have also been planted for erosion control, fire breaks, forage for livestock, and in pollinator-friendly gardens. Flax seeds, a common ingredient in bird seed mixes, provide food for birds and other small animals. All this to say, humans and flax share a long history together, and it deserves a place in your garden.

The flax species profiled here is actually two species: Linum lewisii and Linum perenne. That’s because these two species look nearly identical and are both used as garden ornamentals and in wildflower seed mixes. They are also both known as blue flax, among myriad other common names. Due to their similiarity, L. lewisii is considered by some to be a subspecies of L. perenne.

Linum lewisii is found across western North America and received its name after being collected by a member of the Lewis and Clark Expedition. The plant collection was brought back from the expedition and determined to be new to western science. It was described and named by Frederick Pursh. Linum perenne is a European species which was introduced to North America as an ornamental and has since become widely naturalized. In 1980, a naturalized selection of L. perenne was released for use in restoration plantings under the cultivar name ‘Appar’ with the understanding that it was L. lewisii. A genetic study later revealed that the cultivar was instead L. perenne. The study also provided evidence that “North American Lewis flax and European perennial blue flax are reproductively isolated,” suggesting that they are indeed two separate species.

Despite being separate species, telling them apart can be a challenge. Blue flax plants grow from a taproot and woody base and are multistemmed, reaching two to three feet tall. The stems are thin yet stringy, wiry, and not easily torn, which helps explain why flax is such a good plant for making textiles. Short, slender leaves are alternately arranged along the length of the stems, while flower buds form at the ends of stems in loose clusters. Flowers bloom early in the day and are spent by the afternoon. They are 5-petaled, saucer-shaped, and a shade of blue – from whitish blue to deep blue – depending on the plant. Small, round, 10-chambered seed capsules form in the place of flowers, each chamber housing one or two flat, shiny, dark brown seeds. Flowers bloom daily in succession up towards the ends of stems even as the fruits of spent flowers lower on the stalk mature.

seed capsules of blue flax

A close look at their flower parts is really the only way you might be able to tell these two species apart. Blue flax flowers have five stamens topped with white anthers and five styles topped with little, yellow stigmas. The flowers of L. lewisii are homostlyous, which means their styles are all the same length and are generally taller than or about the same height as the stamens. The flowers of L. perenne are heterostylous, which means their flowers can either have styles that are much longer than their stamens or stamens that are much longer than their styles. Each plant in a population of L. perenne has either all long-styled flowers or all short-styled flowers. In a mixed population of L. perenne and L. lewisii, separating the long-styled L. perenne plants from the L. lewisii plants presents a challenge (at least for me).

long-styled blue flax flower
short-styled blue flax flower

Due to the similarity of these two species, it’s easy to see how the plants or seeds of blue flax could easily be mislabeled and sold as one species even though they are the other species. This could be a problem in a restoration planting where seed source and identity is critical, but in your garden, it’s really no big deal. Both species are great for waterwise and pollinator gardens. They are equally beautiful and easy to grow and care for. If nothing else, perhaps the challenge in identifying them will encourage you to take a closer look at your flowers and familiarize yourself with their tinier parts – an act all of us amateur botanists could stand to do more often.

The photos in this post were taken at Idaho Botanical Garden in Boise, Idaho.

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Drought Tolerant Plants: Yellowhorn

A drought tolerant garden doesn’t have to be treeless. While the pickings are slim, there is a selection of trees that, once established, are well adapted to deal with extended bouts of little to no water. One such tree is yellowhorn, a species that demands to be considered for any waterwise landscape. Yellowhorn is rare in cultivation – and also restricted in its natural distribution – but perhaps that will change as word gets around about this beautiful and resilient tree.

Xanthoceras sorbifolium is native to several provinces in northern China and has been cultivated in a number of places outside of China since at least the 1800’s. Its ethnobotanical value is well understood in China. Its leaves, flowers, and seeds are edible and medicinal, and the high oil content of its seeds make them useful for the production of biofuels. Researchers are also investigating the use of yellowhorn for ecological restoration in arid habitats where desertification is a concern.

yellowhorn in bloom

Yellowhorn is the only species in the genus Xanthoceras, but is one in a long list of trees and shrubs in the Sapindaceae family – a family that now includes maples and horse chestnuts. It is considered both a large shrub and a small, multi-stemmed tree. It reaches a maximum height of about 25 feet, but arrives there at a relatively slow pace. It tolerates a variety of soil types, but like most other drought tolerant plants, it prefers soils that don’t become waterlogged easily. Its leaves are long, glossy green, and compound, consisting of 9 – 17 leaflets. The leaves persist late into the year and turn yellow in the fall. However, late spring, when the tree is covered in flowers, is when this tree puts on its real show.

Large white flowers with yellow-green centers that turn maroon or red-orange as they age are produced on racemes at the ends of branches. Small, yellow, hornlike appendages between each of the five petals of the flowers are what gives the tree its common name. Flowering lasts for a couple weeks, after which fruits form, which are about 2.5 inches wide, tough, leathery, and somewhat pear shaped. In my experience, most of the fruits are eaten by squirrels long before they get a chance to reach maturity. The ones the squirrels don’t get will persist on the tree, harden, and eventually split open to reveal several large, dark, round seeds nestled in chambers within the fruit.

To truly appreciate this tree, it must be seen in person, especially in bloom. At that point you will demand to have one (or more) in your garden. The seeds are said to be delicious, so you should give them a try if you can beat the squirrels to them. For a more thorough overview of yellowhorn, check out this article from Temperate Climate Permaculture, and for more photos of yellowhorn in bloom, check out this post from Rotary Botanical Gardens.

Squirrel nesting in yellowhorn, getting ready to go after more fruits.

All photos in this post were taken at Idaho Botanical Garden in Boise, Idaho.

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Drought Tolerant Plants: Water Efficient Garden at Idaho State Capitol Building

water efficient garden sign

As drought and threats of drought continue in the western half of the United States, as well as in many other parts of the world, people are increasingly looking for ways to use less water in their landscapes. For many it is a change they are reluctant to make, worried that they will have to sacrifice lush and colorful yards and gardens for drab, dry, gray, and seemingly lifeless ones. Not so, though. The palette of plants that can survive in low water environments is actually quite diverse and contains numerous plants that are just as lush and colorful as some water hogging ones. If planned, planted, and maintained well, a water efficient garden can be incredibly attractive and can even consist of some plants that are comparatively more heavy water users. So, for those who are apprehensive about getting down with brown, don’t fret – there is a better way.

How does one go about creating such a garden? The answer to that is a book on its own – much too long for a single blog post. It also depends who is asking the question, or more specifically, where they are asking it from. Luckily, demonstrations of water-wise gardens are becoming more common. These gardens, planted with regionally appropriate plants and showcasing various water-saving techniques, are great places to start when looking for ideas and motivation. Such gardens can be found at public parks, city and state government buildings, botanical gardens, nurseries and nursery centers, and water company offices. If you are looking to transform your landscape into a more water efficient one, seek out a demonstration garden in your area. It’s a great place to start.

There are several such gardens where I live, one of which is the Water Efficient Garden at the Idaho State Capitol Building in Boise, Idaho. This garden began in 2010 as a partnership between United Water Idaho and the Idaho Capitol Commission. Its mission is to introduce visitors to “low-water native and adaptive plants that thrive in Idaho’s climate.” The plants that were selected for the garden are commonly found at local garden centers and nurseries – an important objective when introducing people to water-wise gardening. The ultimate goal of this garden is to “show homeowners that they can maintain attractive landscaping while conserving water.”

I have my criticisms of this garden regarding plant selection, design, etc., but I’ll spare you those details. I also don’t know the specifics about how this garden is maintained or how often it is watered. All that aside, I am just happy that it exists, and I encourage you to seek out similar gardens in your area. There are numerous approaches to designing and constructing water efficient gardens – again, a book on its own – but demonstration gardens like this are an excellent place to get ideas and learn what other people in your area are doing to conserve water and create landscapes that better reflect the ecology of your region.

United Water Idaho offers a brief introduction to low water gardening here, as well as a list of plants that are in the capitol building garden here.

Blanket Flower (Gaillardia x grandiflora 'Goblin') Plants in the garden are accompanied by a sign with a number on it. The sign corresponds to the plant list that is provided at the entrances to the garden.

Blanket flower (Gaillardia x grandiflora ‘Goblin’). Plants in the garden are accompanied by a sign with a number on it. The sign corresponds to a plant list that is provided at the entrances to the garden.

Dianthus sp.

Dianthus sp.

Coreopsis sp.

Coreopsis sp.

Geranium sp.

Geranium sp.

Liatris sp.

Liatris sp.

A drift of pearly everlasting (Anaphalis margaritacea)

A drift of pearly everlasting (Anaphalis margaritacea)

Purple coneflower (Echinacea purpurea)

Purple coneflower (Echinacea purpurea)

Yellow ice plant (Delosperma nubiginum)

Yellow ice plant (Delosperma nubiginum)

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Drought Tolerant Plants: Prickly Pears

In the introduction to this series about drought tolerant plants, I defended water efficient gardens by claiming they don’t have to be the “cacti-centric” gardens that many visualize upon hearing terms like “xeriscape,” “water-wise,” and “drought tolerant.” And this is absolutely true. However, that won’t stop me from suggesting that such landscapes include a cactus or two. Despite their menacing and potentially dangerous spines, they are actually quite beautiful, and a cactus in bloom is really a sight to behold. Together with a variety of grasses, herbaceous flowering plants, and shrubs, cactus can add unique forms, textures, and focal points that will enhance the look and function of a water-wise garden. This is why I recommend considering cactus, particularly (as far as this post is concerned) one of the many varieties of prickly pears.

The cactus family (Cactaceae) has a native range that is limited to the Americas. Within that range it is expansive, and cactus species can be found in diverse regions from Canada down to Patagonia. The genus Opuntia (the prickly pears) is the most widespread of any genus in the cactus family consisting of at least 300 species found throughout the Americas. Even a brief investigation into Opuntia will reveal that there is considerable controversy as to how many species there actually are and what to call them. This is partly due to the large ranges that species in this genus can have and the diverse habitats they can be found in within those ranges, resulting in a single species having many forms, varieties, and/or subspecies. Hybridization is also common in this genus where ranges overlap, augmenting the challenge of identification.

Generally, prickly pears have flattened stems with spines and glochids emerging from small bumps called areoles. Their flowers are large, showy and a shade of either yellow, orange, or pink and sometimes white. They form fruits that are either fleshy and juicy with a red or purple hue or hard, dry and a shade of brown or tan. The flattened stems are called pads or cladodes and can be quite large in some species, while diminutive and sometimes rounded in others. Some species are without spines, but all have glochids – tiny, barbed, hair-like structures found in clusters on the stems and fruits. While the spines can be painful when they penetrate skin, the glochids are far more irritating as they easily detach themselves from the plant and work their way into the skin of their victims. The fleshy fruits, called tunas, can be eaten after first taking care to remove the glochid-infested outer layer. The young stems of many species can also be eaten – they are referred to as nopales and are common in Mexican cuisine.

Flowers of Opuntia sp. with bee inside flower on the left

Flowers of Opuntia sp. with bee inside flower on the left

Again speaking generally, prickly pears are very easy to propagate and cultivate. Their two main preferences are full sun and well-drained soil. If you are worried that the soil you are planting them in is going to stay too wet for too long, amend it with some gravel. This is especially important if you live in a climate that receives lots of precipitation or that has cold, wet winters. Once established, prickly pears will move around the garden. If that becomes a problem, expanding plants are easily pruned and traveling plants are easily removed.

I live in a climate that requires the selection of cold hardy prickly pears, so I am taking my specific recommendations from two books: Cacti and Succulents for Cold Climates by Leo J. Chance and Hardy Succulents by Gwen Moore Kelaidis. If you live in a warmer climate, your options will be greater. Still, the options for cold regions are pretty numerous, so for the sake of space I am narrowing my list down to a handful that stand out to me at this particular moment.

Three eastern United States species of prickly pears (O. compressa, O. macrorhiza, and O. humifusa) are, according to Chance, “more capable of dealing with wet and cold conditions than almost any other members of the cactus family.” They still require well-drained soil though. An appealing trait is their large, juicy, red fruits that can add garden interest in late summer and fall. Opuntia engelmannii is another species with the potential to tolerate cold, wet conditions. Its size is appealing to me, with pads that reach a foot wide and plants that grow several feet tall. Chance advises finding “a clone that is known to be cold tolerant” and making some space for it, “as it becomes huge in time.” The most cold tolerant prickly pear may be Opuntia fragilis. It is a diminutive plant with a large native range and a variety of forms, some with rounded pads “shaped like marbles.”

Fruits ("tunas") of Opuntia engelmannii - photo credit: www.eol.org

Fruits (“tunas”) of Opuntia engelmannii – photo credit: www.eol.org

Opuntia fragilis 'Frankfurt' - photo credit: wikimedia commons

Opuntia fragilis ‘Frankfurt’ – photo credit: wikimedia commons

Opuntia polyacantha is a prickly pear native to my home state, Idaho. It is found at high elevations throughout the Intermountain West and is also found on the Great Plains. It has many forms and varieties, and its flowers are various shades of pink or yellow. It is a fast growing species and spreads around easily. Other cold hardy species include Opuntia macrocentra (which has a very attractive yellow flower with a red-orange center), Opuntia erinacea (commonly known as hedgehog prickly pear for its abundant, long spines that can obscure the pads), and Opuntia microdisca (a tiny Argentinian prickly pear with pads that barely reach an inch across but, as Chance says, “works very well in a dry rock garden with other miniatures”).

Pads of Opuntia polyacantha

Pads and spines of Opuntia polyacantha

A post about Opuntia could go on indefinitely due to the sheer number of species and their diverse forms and attributes. This is meant merely to pique your interest. The flowers, if nothing else, should certainly interest you. In her book, Kelaidis calls them “improbably beautiful,” and goes on to say that they are “often papery, always glistening and showy.” Chance likens them to “any fancy rose” because they are “extraordinarily large, brightly colored, [and] eye catching.” Next week, as part of Awkward Botany’s Year of Pollination, I will present another reason to be fascinated with the flowers of Opuntia. For now, I will leave you to ponder this word, “thigmonasty.”

Want to learn more about prickly pears? Check out Opuntia Web.