Friday Fractal XLI

While here in Colorado, freezing rain and snow is drizzling from the skies, spring is sweeping across the northern hemisphere. In celebration, I designed this petal-like Julia set and laid it on top a wavy Mandelbrot set, creating this arousing union. (What can I say? It's spring!)

In creating the fractal, I used the colors from this native Colorado wildflower, which will be blooming here, very shortly:

Bell's Twinpod (Physaria bellii)

These pretty little blooms are only found in Colorado, and even then only in certain areas. Specifically, the plant grows in sandstone or shale formations (the Niobrara, Pierre, Lykins, and Fountain formations) along the hogback near Boulder, in a narrow band just over a mile in elevation (between 1580 and 1760 meters.) This limited range is a problem for P. bellii, as residential development and limestone mining have been minimizing the flower's habitats. With few and fewer populations, P. bellii may not be able to sustain the genetic diversity necessary to endure. CSU PhD candidate Linda Kothera, of the Colorado Native Plant society, has been researching the threat to the native plant. She found that the species was limited to two counties, Boulder and Larimer. In Jefferson County (where I live) the species has hybridized with the closely related (and more common) species, P. vitulifera. Linda's research showed that individual, isolated populations of P. bellii were genetically distinct, but still able to interbreed. Still, these advantages may not be enough to save the flower, which currently has no formal protection. As Linda writes:

My study generated evidence that the purported hybrid populations of P. bellii and P. vitulifera in Jefferson County are indeed hybrids. It is good news that P. bellii does not appear to be threatened by hybridization with P. vitulifera at this time. However, the results from this study indicate P. bellii is confined to just two counties in Colorado, Boulder and Larimer. Furthermore, the results from the population genetics part of my research indicate that each population makes a unique contribution to the genetic diversity of the species as a whole. The loss of even a few populations could alter the current pattern of gene flow, which could reduce levels of genetic diversity.

Physaria bellii faces the very real threat of loss of habitat from residential development and limestone mining. Conservation efforts should thus involve monitoring populations to ensure that levels of genetic diversity remain stable, as well as ensuring a significant proportion of populations (there are less than 30) are not lost to human activities. As P. bellii lacks formal protection, the impetus for this work will likely fall to the cities of Fort Collins and Boulder, as well as Larimer and Boulder county open space programs.

This would indeed be a shame. There is much to be said for a unique flower in a unique location. In some areas, fossils can be found in the sedimentary rocks in which the plant takes root. Here is one small outcropping of P. bellii near a clam (Inoceramus) fossil in an outcrop of shale near Boulder:

The photographer who captured this image, Jeff Mitton, also captured the fragile, fleeting essence of P. bellii's plight, on his site:

In an evolutionary sense, specialists may have a tenuous grip on life. If a species, such as a clam, is narrowly adapted to the environment in which waves pound against sandy beaches, the species is guaranteed a safe haven. Since our planet has had oceans, waves have been pounding against beaches, and that will probably never change. If, on the other hand, a specialist depends on other species, or on environments that appear and then disappear, the specialist will probably not last very long, on a geological or evolutionary scale. Bell's twinpod grows on shale, but shale is not permanent.

Erosion brings shale outcrops to the surface, where they weather, erode, and disappear. If another outcrop does not appear as a shale outcrop disappears, the stranded population is doomed. Furthermore, miniscule populations are more likely to suffer calamities that wipe them out.

The shale outcrop at the west end of Neva Road is novel not only because it supports Bell's twinpod, but also because it presents a stark contrast of persistence in evolutionary time. Bell's twinpod grows among fossils of large, robust marine clams. The clams, in the genus Inoceramus, persisted for 135 million years. It is a delightful juxtaposition: a small, fragile plant, probably not destined for a long play in this world, grows among the stony impressions of a species that endured for eons.

This summer,if you happen to be hiking in the foothills of the Front Range, be sure to keep an eye out for Bell's twinpod. You can be sure, I will be.

Image of Bell's Twinpod (large) by Dave Powell, USDA Forest Service, via www.forestryimages.org, with clam fossil by Jeff Mitton, fractal created by the author using ChaosPro