Our Window on Nature

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Desert Wildflowers

Filed under: Flowers — Lowell Christie -- March 1, 2006 @ 2:46 pm

OcotilloEarly rains came to the desert again this year, and with any luck we’ll meet April in the midst of fields of wildflowers. Wildflowers on the desert? A most unlikely place.

Too many RVers experience the desert only during the heat of summer. They seek to escape, hurrying through on their way to somewhere cooler. And outside their window stretches the dry landscape, blowing dust and searing heat that drives away all but the confirmed desert rat. But deserts have another side, best seen during early April when spring arrives in this arid land.

The key to a dramatic desert spring is the proper amount of rain falling at precisely the right time of year. That means there is great variation in the spring wildflower show from one year to the next. While even a year of relatively little rainfall brings displays of cactus blooms and various herbs if you know where to look, a wet year turns the desert into a sea of green. And a first-time visitor doubts the existence of a desert anywhere in the Southwest.

The reason for this variation lies in the lifestyle of desert plants called ephemerals. Their name comes from their fleeting existence in plant form; here today – gone next week, returning only when conditions are favorable. And those conditions may not re-occur for many years.

Dryness is a fact of life on the desert, and even plants that have adapted to an arid habitat need moisture to bloom and set seed. In more temperate areas plants can take their chances, assuming that it’s spring whenever the light conditions and temperature seem agreeable. On the desert that routine could prove fatal.

Instead, desert “annuals” may actually have to wait for several years before sprouting. Their main triggering factor is moisture, although temperature and light play a part in insuring that the flowers blossom in the appropriate season. Some deserts have two “wet” periods each year, but each plant species must choose its correct season or not survive even though moisture is present.

The seeds of desert ephemerals are covered with a special “inhibitor” that prevents sprouting. It requires at least one-quarter inch of rainfall to wash off the inhibitor, and the moisture must occur within a short period of time. If the rain is sporadic or arrives at the wrong season, the plant ignores the signal and continues to wait. If necessary, it regenerates another inhibitor coating to replace that which was partially washed away. Then, when all conditions say go, the plant bursts into action.

As desert flower-lovers we know that certain conditions precede the best displays, so each year we listen to the desert weather reports regardless of where we might be. First we watch for the relatively heavy fall or early winter rains needed to dissolve the seeds’ inhibitor coatings. Then we hope for mild winter temperatures in order to give the plants optimum conditions for germination. The arrival of light showers in February and March means the hills and valleys will suddenly burst into bloom, flooding the landscape with color.

The best flowering years are seldom sequential – as an average they fall about eight years apart. On these special years we try to arrange our travel schedule to include April in southern Arizona’s Sonoran Desert, for we consider it to be the greenest and most varied of the North American deserts. Even in more “normal” years you may find us there, however, because the fleeting blossoms of ephemerals are only one chapter of the story of a desert spring.

Ephemeral plants avoid the harshest months of the desert year by surviving as seeds, but other plant species have evolved into pioneers hardy enough to endure the heat and dryness. And any plant that can grow under such adverse conditions seems to take on new vigor when it gets a little help from the rainy season.

For much of the year many desert plants come clothed in olive and gray. The ubiquitous creosote bush has a waxy coating on its leaves, while other plants such as the ocotillo lose their leaves entirely, becoming weathered sticks that seldom merit a second look except as a curiosity. But add a little water in the spring and the picture changes.

Shrunken creosote leaves become shiny with the added moisture, giving off the resinous scent so characteristic of the desert after a rain. Soon the plant sports tiny yellow flowers, followed later by white polka dots of seed balls all over its branches.

The ocotillo makes an even more startling transformation – adding dark green leaves to its gray bark, and topping each stem with a flowery red flag. Ground-hugging plants such as the various cactus species contribute to the display; huge fragile flowers burst out to make you forget the leg-piercing spines that are the most memorable feature during the rest of the year.

Early April is the ideal time to visit the desert. Here is where spring crosses the Mexican border. The air is clear, and from higher elevations you can spot fields of wildflowers from many miles away. Wildflowers in the desert? Count on it. And every few years this springtime show is truly a floral extravaganza.

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