The garden may be under snow at the moment but the sun feels warmer every day, the snow is rotting, and soon one of my favorite spots in the garden will be exposed. This spot is the area we call the ‘desert,’ the hottest, driest part of the garden where the plant community is comprised of the plants that love the sun, tolerate drought (i.e. they are fine with 13” annual rainfall as their only source of water) and remain standing in the face of the west winds.
This is not really a desert but it’s an area that is south facing, sits on a slope, uses lots of rocks to hold heat during our cool nights, doesn’t get much water and has clay soil (some of which was amended to improve drainage.) It ACTS like a desert. The plants are species found in Montana’s short prairies and rocky plateaus – species that are becoming increasingly popular as people gain interest in xeric landscaping.
I love the plants in this ‘desert.’ They are resilient and tough. It seems like they are always changing. Plants move from one spot to another, a few take hold and grow bigger than they were supposed to, new colonies of seedlings emerge, and there are always some fantastic displays of color. Although some plants do succumb to the elements, most have some incredible mechanisms for survival and reproduction that allow them to thrive.
Plants in hot, dry communities have strategies for surviving in adverse climactic conditions.
Some species (e.g. Sagebrush, Scarlet Globemallow and Arrowleaf Balsamroot) have deep root systems and taproots that allow them to find water deep beneath the surface even in times of drought. These deep-rooted species often function as nurse plants providing shade and moisture for emerging seedlings and plants that may take years to fully develop.
Other species (e.g. Fringed Sage, Blue Grama, Cutleaf Daisy, Sagebrush Lily and Mountain Sandwort) have shallow roots that allow them to grow in close proximity to deep rooted species, often under canopies provided by deep rooted plants where they are somewhat shaded. Most drought resistant plants with shallow roots have very finely textured leaves that minimize transpiration.
A number of species have waxy or succulent leaves – usually evergreen – as a mechanism for surviving drought. Their leaves are able to close stomata in response to heat or low humidity to restrict movement of air and water, thereby remaining turgid even on the hottest day of summer. Stonecrop, Yucca and Shining Penstemon are good examples of this.
Montana’s state flower, the Bitterroot, has an unusual strategy for survival. Its succulent leaves emerge in fall, remain under the snow all winter, then shrivel and fall off as the plant begins to bloom leaving only the showy flowers. The flowers quickly produce seed (early June) and then the entire plant senesces (goes dormant) until fall, thus avoiding all of summer’s adverse weather.
Survival is not just about overcoming adverse climate. In order to survive being consumed some plants, including Cacti, produce spikes and thorns. True, Montana doesn’t have near the number of cacti as the southwest, but there are a few species here. Foxtail, Spinystar, and Simpson’s Hedgehog Cacti as well as two species of the ubiquitous Prickly Pear are found in the state. Although these are difficult, no, AWFUL to weed around in a garden (I use needle-nose pliers), watching green sweat bees wallowing their gorgeous flowers make having them in a garden worthwhile.
‘Desert’ plants have also developed strategies to maximize reproduction in adverse climates.
One of their most common tactics is to remain dormant until sufficient rain provides the right conditions and then to rapidly flower, produce seed and senesce before summer gets started. In Montana these ephemeral species include low growing cushion plants like Douglasia, Moss Campion and Phlox species. Several species of Larkspur, Biscuitroot and Buttercups are other early flowering species in hot, dry areas.
Some of my favorite desert plants have the most amazing fragrances to attract pollinators from far and wide, thus ensuring a good crop of seeds. White Evening Primrose and Western Wallflower are prime examples.
Another tactic employed by a number of species is to produce hundreds of seeds from each plant attempting to reproduce. Typically dozens of germinants appear each spring hoping for enough moisture to establish roots before summer sun forces them into dormancy or death. A few survive and a new generation begins. A number of Penstemons (including Firecracker, Shining, Fuzzy-tongue, Hotrock, and Lyall’s Penstemon) are good examples of this. Another example is Dustymaiden whose seedlings you can see in the background of the photo of the Plains Prickly Pear.
Others plants (including Scarlet Gilia and many Lupines) use the strategy of producing seeds over periods of several months hoping to find just the right conditions for the seeds to find their way into a crack or crevice without become completely dessicated by sun and wind. Gilia has the additional strategy of spending an entire season as a prostrate rosette, building up root mass and storing sugars in preparation for its dramatic flowering during its second season.
Perhaps what I love about the desert plant community is metaphoric. These plants grow and prosper despite the elements. They are persistent. They use various strategies and mechanisms to allow them to survive and thrive and they just keep on. They are part of a community that perseveres and thrives in adverse conditions and they are beautiful in the process. What a great metaphor for life!
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