Reasons for Wildflower Diversity
California provides a wide variety of conditions (link to Western Regional Climate Center Web site) for plant growth. In each area, we find the plant species that can take advantage of resources available in that specialized set of conditions. Plants adapt to certain conditions by producing specialized structures and evolving growth habits corresponding to local environmental pressures and opportunities. Thus, each species persists in the areas with the best combination of soil, moisture, temperature, light, and other factors for its growth. We can grow plants in cultivation far outside of their natural range, but in nature they must compete with other plants for limited resources.
Topography and Elevation
With topography ranging from low basins to high mountain peaks, California offers a huge range of elevations. Only certain plants are adapted to grow at each elevation.
- At 14,491 feet above sea level, Mt. Whitney in the Sierra Nevada mountains of California is the highest point in the continental United States.
- At 282 feet below sea level, Badwater in Death Valley, California is the lowest point in the western hemisphere.
Aspect and topographic position make a difference in vegetation.
Geology, Soils, and Substrate
Soil types depend on the underlying geology (rocks), climate, vegetation, and the amount of time that rocks have had to break down into soil. The soil texture, depth, and nutrient content influence which plants can grow there. Aquatic plants grow in the water. They may be rooted in the soil or they may have floating roots. Aquatic plants are affected not only by soil factors but also by water chemistry, depth, and temperature. Plants growing in salt marshes, estuaries, and marine systems are also influenced by tides.
Most of California has a Mediterranean climate, with cool, wet winters and hot, dry summers. But some areas are cool and moist year-round, and some of our deserts experience summer monsoons.
Climatic factors that affect plant growth include:
- total amount of precipitation
- less than 2 inches of rainfall annually in Death Valley
- up to 200 inches in the north Coast Range
- form of precipitation (rain, snow)
- timing of rainfall (winter, summer, year-round)
- the ratio of precipitation to evaporation
- high and low temperature extremes
- length of the growing season
- occurrence and seasonality of fog