There is yellow, and then there is the YELLOW of the mariposa lily, Calochortus clavatus. Remarkable in its brightness and purity, its yellow is one of the most intense and vibrant concentrations of color I have seen in the chaparral.

It is relatively uncommon, and this is one of a few seen along trails in Rocky Peak Park, and the Simi Hills. Of the varieties listed in the Jepson Manual, this appears most similar to the slender mariposa lily (Calochortus clavatus var. gracilis).

The insect emerging from the flower is a small bee -- probably a sweat bee (Halictidae). These bees were found on several of the mariposa blossoms along the trail. They were usually busy slurping nectar from the gland near the base of each petal, and partially hidden by the club-like hairs that gives the species its name.

From a run earlier this week in Rocky Peak Park.

Related posts: Mountain Mariposa, Plummer's Mariposa Lily

Technorati Tags: mariposa lily

Indian warrior's varying tones of carmine contrast sharply with its lush green leaves and create a striking combination of colors when seen along a trail. Surprisingly, it is the green of its leaves that is one of its interesting features.

Updated 03/13/08.

My run of the "keyhole loop" at Ahmanson Ranch started out as a tempo run -- not so much as being part of a rigorous training program, but because of a dead battery in my car remote. It felt good to push the pace a bit.

Part way through the loop, running up a short hill into the sun, I was struck by a repetitive pattern of backlit leaves in the new growth on and alongside the road. Like little green satellite dishes, hundreds of the round leaves of mallow (Malva neglecta) were facing directly into the late afternoon sun.

Mallow (Malva spp.) is an invasive plant from the Mediterranean area that has flourished in Southern California's Mediterranean climate. In most years, it is very common. I've run and hiked past thousands of these plants, but never noticed this synchronicity.

Tracking the sun makes sense. Our climate has an extremely variable and relatively short growing season. A plant that maximizes its intake of solar energy and growth by orienting its leaves toward the sun would have an advantage over a less adaptable species. This is probably one of the reasons mallow is such a successful invasive. Another invasive that grows alongside mallow, black mustard, also appears to exhibit heliotropism as it is growing. It creates a rosette of leaves facing into the sun by raising leaves on the side of the stalk away from the sun, and lowering leaves on the side of the stalk toward the sun.

From a run during the week at Ahmanson Ranch -- now Upper Las Virgenes Canyon Open Space Preserve.

Technical papers:

Diaphototropic Movement of the Leaves of Malva Neglecta
H. C. Yin
American Journal of Botany, Vol. 25, No. 1 (Jan., 1938), pp. 1-6

HELIOTROPISM AND WATER AVAILABILITY EFFECTS ON FLOWERING DYNAMICS AND SEED PRODUCTION IN Macroptilium lathyroides
ARMANDO MARTINS DOS SANTOS, LUIS MAURO GONÇALVES ROSA, LUCIA BRANDÃO FRANKE, CARLOS NABINGER

Listed by the California Native Plant Society as being rare, threatened, or endangered, Santa Susana tarweed (Hemizonia minthornii) can be found where sandstone outcrops of the Chatsworth formation occur, such as in the Santa Susana Pass area in the Simi Hills.

This photograph was taken on a run at Sage Ranch on October 1, 2007.

Maybe it's the result of record low rainfall, or the 2005 Topanga Fire, or a combination of the two -- there has been a dramatic increase in the amount of tumbleweed (Salsola tragus) along the dirt roads in Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch).

Like black mustard, and milk thistle, tumbleweed is an invasive plant. According to UC IPM Online tumbleweed is native to southeastern Russia and western Siberia and was first introduced into the United States (South Dakota) in 1873.

The photograph of the tumbleweed flower was taken on a run at Ahmanson Ranch on October 3, 2007.

Some related posts: Dealing With Drought, Milk Thistle Seed Heads, Curly Dock

Who hasn't pondered the intriguing network formed by the interconnected veins of a leaf? Like many apparently complex self-organized structures, there is a recognizable pattern, but the basis of the pattern is difficult to grasp.

Remarkably, research published in 2002 (S. Bohn et al., Phys. Rev. E, June 2002.) found that there is a simple relationship governing the angles between vein segments in the leaves of dicotyledons, and that this relationship is universal. The study also found that the observed vein angles can be reproduced using a simple force model.

Numerical analysis of leaf scans revealed that the angles between vein segments are directly related to the thickness of the segments. When the vein sizes are similar, the connection appears to form a three-way junction with the angle between the veins about 120 degrees. If the vein sizes are dissimilar, with one much larger than the other, the smaller vein joins the larger at about a 90 degree angle.

The photograph is of a leaf of a Fremont cottonwood (Populus fremontii) along Las Virgenes Creek in Upper Las Virgenes Canyon Open Space Preserve. It was taken on a run from the Victory trailhead on May 16, 2007.

Mariposa lilies (Calochortus invenustus) blooming through the palmate leaves of a lupine at about 8500 ft., near Sawmill Mountain, west of Mt. Pinos.

According to data from the Consortium of California Herbaria, this species was documented in the Mt. Pinos area as early as 1897.

The wasp-like insect is a hover fly, probably Chrysotoxum festivum.

From Sunday's Mt. Pinos-Mt. Abel Out & Back run.

Related posts: Plummer's Mariposa Lily, Bee Fly On Western Wallflower

In a Spring in which there has been little rain and a reduced number of wildflowers, the vibrant yellow of gumplant has been a welcome sight along Ahmanson's main trail in Upper Las Virgenes Canyon Open Space Preserve near the Victory trailhead.

This appears to be Grindelia hirsutula var. hirsutula, a species considered rare in Ventura County. It is reported that a species of gumplant was used medicinally by the Chumash, and other native peoples within its range, for treatment of pulmonary problems.

Pine drops (Pterospora andromedea) and snow plant (Sarcodes sanguinea) are related nonphotosynthetic plants that are found under pine and related trees, primarily in the mountains of the western U.S.

At one time it was believed that these plants were saprophytes, and obtained needed nutrients directly from decaying organic matter in soil. However, research has revealed a more complex parasitic relationship in which the plant obtains carbohydrate from a pine tree, by way of a shared mycorrhizal fungus.

The photograph was taken on the run described in Heat Wave, on July 16, 2006.

Related post: Snow Plant

This prickly pear on Lasky Mesa appears to have many of the characteristics of the Engelmann prickly-pear, Opuntia engelmannii, but is more likely a cross involving O. engelmannii. One such cross is O. littoralis X (O. engelmannii X O. phaeacantha ) which is referred to as O. ×occidentalis in the Jepson Manual. Here's a closer view of the stamens and pistil.

From a run in in Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch) on May 23, 2007.

Blue oak (Quercus douglasii) is a characteristic oak of the lower elevations of the Sierra foothills and coastal mountains, its range essentially encircling California's Central Valley.

Based on its reported range, Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch) contains one of the southernmost populations of blue oak within its range. However, the predominate deciduous oak in the area is valley oak (Quercus lobata), and occurrences of blue oak appear to be rare. Regional climate modeling suggests that over the next century the range of blue oak could shift northward and diminish to nearly 60% of its current range.

Blue oak is reported to hybridize with valley oak, however a 2005 study suggests hybrids of these species may be more rare than generally accepted.

The photograph of the leaves of a blue oak was taken on a run along East Las Virgenes Canyon to Lasky Mesa on April 24, 2007. A valley oak immediately adjacent to this blue oak was killed in the 2005 Topanga Fire.

Related posts: Valley Oak Savannah, Laskey Mesa Oak

Technical papers:

Modeled regional climate change and California endemic oak ranges.
Kueppers, L.M., M.A. Snyder, L.C. Sloan, E.S. Zavaleta, and Brian Fulfrost. 2005. 
Proceedings of the National Academy of Sciences of the United States of America, 102(45): 16281 – 16286.

Limited hybridization between Quercus lobata and Quercus douglasii (Fagaceae) in a mixed stand in central coastal California.
Kathleen J. Craft, Mary V. Ashley and Walter D. Koenig.
American Journal of Botany. 2002;89:1792-1798.

As evidenced by their survival, native plants are generally well adapted to the environment in which they live. Fire, flood, drought, heat or cold, they've seen it all – or nearly so.