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It should be a banner year for blooms
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| A seldom-seen winter annual, the desert five-spot is the sign of a good bloom. |
By Mark Wheeler / For the Hi-Desert Star
After two colorless years that came and went with only the faintest and very localized bloom of spring wildflowers in this corner of the SoCal desert, wildflower watchers will be pleased to know that this spring our floristic fortune is about to change for the better. In fact, the early-bird botanists have discovered the bloom is already under way in some locations, and the evidence of young plants everywhere breaking ground to claim their places in the sun gives good cause to expect that spring 2008 is going to mount a show most definitely worth seeing.
Predict with caution
Because of the complexity involved in the germination of wild winter annuals — the plants we know as spring wildflowers — experts agree that predicting desert blooms with any reliable, year-after-year accuracy is still more art than science. Although the basic mechanism of blooming is rigidly determined by biological laws, the many environmental conditions that play vital roles in the process are eminently changeable and are sometimes difficult to measure with any precision on a regional basis. Rainfall is a good example.
Speaking for winter annuals in both the Sonoran and Mojave deserts in “A Natural History of the Sonoran Desert,” botanist Mark Dimmitt states that an inch or more of rainfall is necessary to “trigger” a widespread bloom. This rainfall must, Dimmitt explains, occur in one rainfall event sometime between end-September and mid-December. Thereafter, as Dimmitt details, “regular rains totaling at least an inch per month through March” are necessary to guarantee a truly notable show.
Volume and timing of the initial rainfall is important because many wildflower seeds demand soaking conditions to open and there must also be sufficient residual moisture in the ground to nurture establishment of root and seedling structure.
Once established, a plant remains at ground level for one to two months through the winter as a rosette of leaves.
In this way, the plant can avoid damage by winter frost, wind and cold temperatures. When days lengthen sufficiently and daily temperatures begin to rise — early February to mid-March in these environs — the plant is poised to carry on with its development very quickly.
Short lifespan
The process of blooming is highly constrained for winter annuals because of their need to complete the entire life cycle, from leaf rosette through flowering to seed production, in 60 to 90 days. This hasty maturation is what allows these plants to survive as a floristic group in the desert.
For the most part, winter annuals avoid harsh desert conditions by remaining underground in seed form until climatic factors — mostly rainfall — stimulate developmental activity.
When they do develop, they spend very little time above ground. Individual plants may survive only two to three weeks, and all the plants for an entire species may disappear from the landscape in just a month or two.
If these plants germinate and try to mature too early or too late in the year, either heat or winter cold might kill them before they can produce seed. Were this to happen too often, their kind would eventually disappear from the landscape. Such an extinction would, indeed, be a tragedy since 40 to 70 percent of all desert plant species, depending on locality, belong to this group, and it contains many of the showiest desert flowers.
There are, of course, flowering trees and many flowering shrubs on the desert landscape and they don’t necessarily abide by winter annual rules. Although many may be spring bloomers and may, in general, follow the winter annual bloom schedule, they are much hardier plants and may take more flowering risks during any given year. Some may even bloom when conditions are poor.
Last spring’s Joshua tree bloom in this region is a case in point. Almost no rain had fallen during the previous eight to ten months and, by all standards of reproductive success, the trees should have remained bloomless. Yet, they bloomed in profusion. Exactly what triggered their display isn’t known, although an episode of extreme cold temperatures that winter is thought to have played an important role in the process.
Freak bloom
Whether there were enough pollinators in the environment during the Joshua tree bloom last year to facilitate any genuine reproductive success remains to be seen. However, even if the bloom wasn’t as successful as it might have been, most of the trees will live to try again.
True winter annuals don’t have such an option. If they don’t get it right the first time, they don’t reproduce and this physiological pressure is responsible for much of the rigid routine in their life cycle.
Yet, for as constrained as they are, spring wildflowers may still deviate from the norm now and then, and for reasons not altogether understood.
For instance, the bloom that is now just getting started was preceded by a wholly unexpected flowering event that occurred from end-October through mid-December. A rainstorm over Labor Day in September provided the water supply and certain locations blossomed with flowers about six to eight weeks later.
Although it’s not at all uncommon for such a rain to produce flowering among shrub species and some perennials, it was surprising to see some species of winter annuals among the flowers making an appearance in the fall. Literally nothing in the popular literature on desert southwest plants addresses such an out-of-season bloom. In fact, ecologist Allan Schoenherr specified in his book, “A Natural History of California,” that “winter annuals can’t be fooled into germinating during the wrong season.”
Don’t miss it
For as much a mystery as the fall bloom of winter annuals remains, many native plant enthusiasts perceived the event as a possible signal for surprises yet to come. Since then, winter rains have been plentiful and a tremendous growth of plants has taken place so far, mostly in the lower elevations where a respectable bloom is already under way.
Many of the more seldom-seen plants are being found and almost all plants in flower are carrying many and quite large blossoms. All of this is a good sign that the season will be noteworthy.
Of course, it’s foolhardy to make any predictions. A spell of hot, dry and windy weather, for instance, could put an end to all spring wildflower hopes in short order.
Barring any such climate challenge, though, this fool’s prediction is that it’s going to be a great wildflower year. Don’t miss it. There’s no telling when we’ll see another one.
Predict with caution
Because of the complexity involved in the germination of wild winter annuals — the plants we know as spring wildflowers — experts agree that predicting desert blooms with any reliable, year-after-year accuracy is still more art than science. Although the basic mechanism of blooming is rigidly determined by biological laws, the many environmental conditions that play vital roles in the process are eminently changeable and are sometimes difficult to measure with any precision on a regional basis. Rainfall is a good example.
Speaking for winter annuals in both the Sonoran and Mojave deserts in “A Natural History of the Sonoran Desert,” botanist Mark Dimmitt states that an inch or more of rainfall is necessary to “trigger” a widespread bloom. This rainfall must, Dimmitt explains, occur in one rainfall event sometime between end-September and mid-December. Thereafter, as Dimmitt details, “regular rains totaling at least an inch per month through March” are necessary to guarantee a truly notable show.
Volume and timing of the initial rainfall is important because many wildflower seeds demand soaking conditions to open and there must also be sufficient residual moisture in the ground to nurture establishment of root and seedling structure.
Once established, a plant remains at ground level for one to two months through the winter as a rosette of leaves.
In this way, the plant can avoid damage by winter frost, wind and cold temperatures. When days lengthen sufficiently and daily temperatures begin to rise — early February to mid-March in these environs — the plant is poised to carry on with its development very quickly.
Short lifespan
The process of blooming is highly constrained for winter annuals because of their need to complete the entire life cycle, from leaf rosette through flowering to seed production, in 60 to 90 days. This hasty maturation is what allows these plants to survive as a floristic group in the desert.
For the most part, winter annuals avoid harsh desert conditions by remaining underground in seed form until climatic factors — mostly rainfall — stimulate developmental activity.
When they do develop, they spend very little time above ground. Individual plants may survive only two to three weeks, and all the plants for an entire species may disappear from the landscape in just a month or two.
If these plants germinate and try to mature too early or too late in the year, either heat or winter cold might kill them before they can produce seed. Were this to happen too often, their kind would eventually disappear from the landscape. Such an extinction would, indeed, be a tragedy since 40 to 70 percent of all desert plant species, depending on locality, belong to this group, and it contains many of the showiest desert flowers.
There are, of course, flowering trees and many flowering shrubs on the desert landscape and they don’t necessarily abide by winter annual rules. Although many may be spring bloomers and may, in general, follow the winter annual bloom schedule, they are much hardier plants and may take more flowering risks during any given year. Some may even bloom when conditions are poor.
Last spring’s Joshua tree bloom in this region is a case in point. Almost no rain had fallen during the previous eight to ten months and, by all standards of reproductive success, the trees should have remained bloomless. Yet, they bloomed in profusion. Exactly what triggered their display isn’t known, although an episode of extreme cold temperatures that winter is thought to have played an important role in the process.
Freak bloom
Whether there were enough pollinators in the environment during the Joshua tree bloom last year to facilitate any genuine reproductive success remains to be seen. However, even if the bloom wasn’t as successful as it might have been, most of the trees will live to try again.
True winter annuals don’t have such an option. If they don’t get it right the first time, they don’t reproduce and this physiological pressure is responsible for much of the rigid routine in their life cycle.
Yet, for as constrained as they are, spring wildflowers may still deviate from the norm now and then, and for reasons not altogether understood.
For instance, the bloom that is now just getting started was preceded by a wholly unexpected flowering event that occurred from end-October through mid-December. A rainstorm over Labor Day in September provided the water supply and certain locations blossomed with flowers about six to eight weeks later.
Although it’s not at all uncommon for such a rain to produce flowering among shrub species and some perennials, it was surprising to see some species of winter annuals among the flowers making an appearance in the fall. Literally nothing in the popular literature on desert southwest plants addresses such an out-of-season bloom. In fact, ecologist Allan Schoenherr specified in his book, “A Natural History of California,” that “winter annuals can’t be fooled into germinating during the wrong season.”
Don’t miss it
For as much a mystery as the fall bloom of winter annuals remains, many native plant enthusiasts perceived the event as a possible signal for surprises yet to come. Since then, winter rains have been plentiful and a tremendous growth of plants has taken place so far, mostly in the lower elevations where a respectable bloom is already under way.
Many of the more seldom-seen plants are being found and almost all plants in flower are carrying many and quite large blossoms. All of this is a good sign that the season will be noteworthy.
Of course, it’s foolhardy to make any predictions. A spell of hot, dry and windy weather, for instance, could put an end to all spring wildflower hopes in short order.
Barring any such climate challenge, though, this fool’s prediction is that it’s going to be a great wildflower year. Don’t miss it. There’s no telling when we’ll see another one.
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