Category Archives: nature

nature, nature|botany, nature|trees, weather, weather|southern california

Ahmanson Blue Oak

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Photograph of leaves of blue oak in East Las Virgenes Canyon.

Update April 14, 2023. The Ahmanson Blue Oak has died. Please see the post Ahmanson Blue Oak Succumbs to Climate Change.

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: Ahmanson Blue Oak Succumbs to Climate Change, Valley Oak Savanna, 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.

nature, nature|weather, nature|wildflowers

Rain Gauge

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The stalk height of Elegant Clarkia (Clarkia unguiculata) is a good indicator of seasonal rainfall.

One of the best indicators of seasonal rainfall I’ve found in the oak woodland and chaparral areas of Southern California in which I run is Elegant Clarkia (Clarkia unguiculata). In a wet year it can grow more than 6 ft. tall. This year it is the shortest I’ve ever observed — about 5 inches in this photo taken near Lasky Mesa.

Related posts: Elegant Clarkia, Dealing With Drought

nature, nature|wildflowers, photography, photography|wildflowers

Holly-leaved Cherry

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The feathery blossoms of the holly-leaved cherry (Prunus ilicifolia) reveal a peculiar flower whose many stamens resemble the tentacles of a sea anemone.

A closer look at the feathery blossoms of the holly-leaved cherry (Prunus ilicifolia) reveal a peculiar flower whose many stamens resemble the tentacles of a sea anemone.

Holly-leaved cherry is a member of the genus Prunus — the same as apricots, peaches, plums and cherries. As is the case with other species in this genus, the seed and leaves may contain hydrogen cyanide. It produces a small, thin-fleshed fruit favored by coyotes.

The photograph was taken on the slopes of Rivas Canyon near Will Rogers State Historic Park, while doing the route described in the post Will Rogers – Temescal Loop. Once again the weather for this (approximately) 21.5 mile loop was post-card perfect. A Google Earth image of a GPS trace of the route is available in the earlier post.

nature, nature|weather, nature|wildflowers, photography, photography|wildflowers, weather, weather|southern california

Dealing With Drought

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Goldfields (Lasthenia spp.) on Lasky Mesa in Upper Las Virgenes Canyon Open Space Preserve.

This photograph of goldfields (Lasthenia spp.) was taken on a run on Lasky Mesa in Upper Las Virgenes Canyon Open Space Preserve (formerly Ahmanson Ranch) almost exactly one year ago.

This April I haven’t seen any goldfields on Lasky Mesa. The soil is too dry for the seeds to germinate. The drought in Southern California has suppressed or delayed the growth of these, and many other species of wildflowers. This is one of the ways that annuals deal with drought — if the growing conditions aren’t appropriate, they don’t grow.

Black mustard, an invasive annual from Europe, is a hardy plant that is a good indicator of Winter rainfall. In 2005 and 2006 the mustard at Ahmanson Ranch was 6′ to 8′ tall and very widespread. This year its growth has been very limited, and the plants are diminutive in comparison.

Plants deal with drought in many other ways, such as dropping leaves, changing the leaf distribution, reducing the size of the leaf, changing the leaf orientation, modifying the shape of the leaf, or changing the leaf color. Flowering may be suppressed, or the flowering time shortened. In some cases the flower may be reduced, or viable fruit may not be produced. Branchlets or stems may be lost. Any life prolonging tactic may be employed when survival is at stake.

According to the NWS, if Los Angeles (USC) receives less than 1.95 inches of rain between now and June 30th, this water year (July 1, 2006 to June 30, 2007) will become the driest since recordkeeping began in 1877. At this point in the season, a new record seems more likely than not.

It was only 5 years ago (2001-2002) that Los Angeles experienced its driest water year so far, recording only 4.42 inches.

Related post: A Little Rain in Los Angeles

nature, nature|wildflowers, photography, photography|wildflowers

Bush Monkeyflower

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Bush monkeyflower (Mimulus aurantiacus) readily hybridizes, producing a myriad of forms and colors.

Bush monkeyflower (Mimulus aurantiacus) readily hybridizes, producing a myriad of forms and colors, and some interesting work for botanists. This plant pictured above may be a hybrid of local salmon and scarlet colored forms.

Update June 10, 2011. The Diplacus section of Mimulus has been the source of much taxonomic turmoil, with the number of species varying from two to 13. Research by Tulig & Clarke found that most named taxa in this group can be distinguished based on morphological characteristics. Accordingly, the monkeyflower pictured above would correspond to a variety of Diplacus longiflorus (Southern bush monkeyflower).

The scarlet variety is sometimes referred to as Diplacus rutilus (Santa Susana bush monkeyflower).

From a run near Sage Ranch on March 26, 2007.

nature, nature|insects, nature|wildflowers, photography, photography|wildflowers

Eastwood Manzanita

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Ants forage among the blossoms of Eastwood manzanita on the Chumash Trail in Rocky Peak Park.

Ants forage among the blossoms of Eastwood manzanita on the Chumash Trail in Rocky Peak Park. From a run on Wednesday, March 21, 2007.

Some related posts: Chumash-Las Llajas Loop, Chumash-Hummingbird Loop, San Fernando Valley from Rocky Peak, Chumash Trail Snow.