Monday, December 14, 2009

Castilleja applegatei

Wavyleaf indian paintbrush - Castilleja applegatei - Scrophulariaceae
Found in the higher elevations and rock canyons of the east side of the Sierra Nevada mountains, C. applegatei is a showy plant with a striking red flower.

These plants are usually found in dry open forests and scrub, particularly rocky areas.

One of the lesser known traits of this plant, and all members of its genus, is that it is a facultative, root, hemiparasite. As a facultative parasite, they are capable of surviving without a host, but grow best with a host, which are typically grasses and forbs.

Thursday, December 3, 2009

Linanthus parryae

Sand Blossom - Linanthus parryae - Polemoniaceae

One of the smallest flowering plants found in the Mojave, Linanthus parryae, also known as sand blossom, is both a prolific and showy little annual. Flowering from March to May, these petite phlox can carpet the hills and washes of the desert with a blanket of purple and white. Endemic to the California floristic provence, the best places to find these little jewels are creosote bush scrub and joshua tree woodlands.

Vegetatively, these plants are rather unremarkable. There is little in the way of an above-ground stem, with only small, spiny leaves ringing what does emerge. However, what they lack in vegetation, they more than make up in blossom. Delicate and showy, the flowers from this plant are a spectacular show in the early to late spring. One of the most striking aspects of these flowers is their polymorphism: populations tend to be either white or blue-purple, and in some cases, a mixture of both.

Because of this polymorphism, these plants have been the subject of genetic studies by several important botanists, including Sewall Wright, who based much of his work on genetic drift on the study this Linanthus.

Friday, November 13, 2009

Larrea tridentata

The Creosote Bush - Larrea tridentata
Family - Zygophyllaceae

In the Mojave's lowlands, one of the most common sights is the creosote bush, a tough, hardy survivor of a plant. Excellently adapted to life as a desert perennial, it has small, waxy leaves and thick cuticle on its stem to help retain moisture.

These hardy plants can survive in extremely dry conditions with little water, making them ideally suited for surviving in the harsh, arid Mojave, which is prone to receive less than 10 inches of rainfall a year. This is due not only to the water retention capacity in their leaves, but the efficiency by which their roots can take up water. In some areas, they're capable of forming almost monospecific stands due to this ability to monopolize all available soil moisture.

Adding to the survivability of these plants is the fact that they are capable of vegetative reproduction by forming what are called "creosote rings." When a mature plant reaches about 30-90 years in age, the old crown will begin to die, then split into separate crowns, forming clonal plants. Over time, these clonal plants will form a clear ring of vegetation. These rings are exceptionally long lived, one reaching over 11,000 years old. This is advantageous for these plants, as seed recruitment requires a very specific set of circumstances, namely two to three years of above average moisture to survive germination. By being able to form colonial clones, they can survive even beyond the "normal" life expectancy without need for continuous recruitment.

Creosote, being a large component of the ecosystem, forms the backbone of many desert communities. In addition to holding the soil together with their extensive root systems, they provide homes for many animals in the desert. One trait that facilitates this is the fact that
these plants tend to accumulate considerable amounts of detritus under their canopies, which provides food and shelter for many desert arthropods and rodents.

Because of the common nature of this plant, it is often ignored in favor of the less common and showier plants of the desert. This is a tragedy, because these plants are among the hardiest, and longest lived, organisms in the Mojave.

Wednesday, November 4, 2009

Living Mojave - an desert botanist's blog

Welcome to Living Mojave, a blog dedicated to the plant life of the northern Mojave desert.

The Mojave is not what people typically envision when they hear the word desert. In the Mojave, we have few sandy areas, few cacti, and a considerable botanical diversity, with an estimated 1500-2000 species of plants, many of which are endemic to the area. The Mojave itself is what's called a cool season desert, meaning that it doesn't receive as much winter rainfall, on average only 10 inches per year, as the warmer Sonoran desert to the south.

While the lowlands tend to have one dominant plant type, the Mojave is riddled with mountains, hills and canyons, all of which have a considerable bio-diversity. This is due to what some scientists call an "island in the sky" effect, which is where plants and animals are isolated by a tract of impassable land rather than water. Evolutionarily, it has the same effect of isolating populations, and producing speciation events. As such, there is considerable evolutionary potential, even from one valley to another.
This blog will attempt to detail some of the species of plant found out in the Mojave, from common and indicator species to rare and special status species.