Tamalpais Manzanita, Mount Tamalpais State Park. Photo: randomtruth.
Serpentine, California’s state rock, is feeling some pressure—and not just because it’s a metamorphic rock! The California Legislature is considering a bill that would strip serpentine of its state rock status; geology blogger Brian Romans explained the details in this recent QUEST blog. Basically, proponents of the bill say that because asbestos is made from serpentine rock, and asbestos causes cancer, serpentine should not be the state rock. Never mind that serpentine does not cause cancer. In fact, many organisms thrive on serpentine soils. And that is what today’s post is about—the unique plants and animals that call serpentine soil home.
Serpentine soil is a tough environment: the soil is coarse, so water runs right through it, making it very dry. It is often dark in color, so it heats up in the sun. And its chemical makeup is challenging to plant life, to say the least. The soil has high concentrations of heavy metals, like nickel, iron, and chromium, and low concentrations of nutrients, like nitrogen and phosphorus. It is also really high in magnesium, which makes it hard for plants’ roots to take up those already-scarce nutrients. And it is low in calcium, which causes ion balance problems for plants.
With nutrients scarce, serpentine inhabitants tend to be small in stature—it’s hard to grow big without much food. And, with low water availability, serpentine plants are drought-tolerant. They often have tough little leaves, which don’t lose much water. Some examples are the Tamalpais manzanita (Arctostaphylos montana), and the Leather Oak (Quercus durata).