Naturally occurring assemblages of plants, called native plant communities, tend to grow together as a response to several environmental factors such as soil type, slope, exposure and availability of sub-surface moisture, etc. While each individual plant species has unique requirements that account for its presence or absence within a general area, considerable overlap in plant distribution often occurs due to the variability of environmental factors and other related habitat conditions. As a result, these communities sometimes merge along relatively indiscreet borders to form mosaic patterns of different vegetation types and varying species composition. In a very general sense, the Thousand Oaks Planning Area contains six native plant communities which are representative of the larger Santa Monica Mountains region.
The Conejo Open Space is home to hundreds of different wildflowers. Although there are wildflowers in bloom almost all of the year, spring is the best time to see vast displays of color along our trails.
Visit the following websites to see pictures of some of the wonderful plants and wildflowers found in our local area.
- Wildflowers of Ventura County
- Wildflowers of the Santa Monica Mountains National Recreation Area
- Wildflowers of Southern California
- CalPhotos: Plants
Chaparral, which is probably the most characteristic vegetation type of Southern California, is found mostly on steep slopes with shallow soils. This plant community consists of a variety of stiff, woody shrubs and usually occurs at higher elevation than the coastal sage scrub zone. Common chaparral plants include chamise, several species of ceanothus, laurel sumac and mountain mahogany. It is located in the foothills south of the Ventura Freeway and on north-facing slopes along the Mount Clef Ridge, Conejo Canyons, and Simi Hills. It is known as a “fire climax” plant community and has adapted to California’s regime of periodic wild fires. Chaparral shrubs provide cover for large animals, serve as a major component in the diet of the mule deer, and produce seeds for birds and small mammals.
Coastal Sage Scrub
Along with chaparral, this is the most widespread plant community within undeveloped areas of the Planning Area. It is comprised of small semi-woody shrubs and is sometimes called “soft chaparral” due to the flexibility of the leaves and stems. Typical coastal sage scrub plants include California sagebrush, California sunflower, California buckwheat and purple sage. The coastal sage scrub community is usually found below 1000 feet where it is present as a band surrounding higher mountains below and often inter-grading with chaparral. Three forms of this plant community occur locally – “inland,” “sea-bluff succulent,” and “maritime.” The inland form is by far the most abundant within the Planning Area and is often called inland sage scrub. The maritime form is present along the Conejo Grade and on south-facing slopes of the Broome Ranch. Like chaparral, coastal sage scrub requires periodic fires or it becomes senescent. The cumulative loss of coastal sage scrub habitat throughout the state has been the focus of considerable concern among biologists. Many of Thousand Oaks’ rarest endemic plants are found within this plant community.
Perhaps the most restricted plant community in the Planning Area, freshwater marsh comprises an accumulation of herbaceous perennial plants generally found wherever water ponds. The best example of freshwater marsh is found along the margins of Lake Eleanor, but it also occurs along slowly moving portions of streams and in the vicinity of livestock ponds. Common plants include cattails, tules and water plantain. Adding to their overall importance, freshwater marshes are utilized as breeding and foraging areas by waterfowl such as cinnamon teal and wading birds such as great blue heron.
Grasslands are characterized by low annual herbs such as black mustard, wild oats and brome grass. In less disturbed areas native grasses, such as purple needle grass, and native bulbs, such as Catalina mariposa lily, may become quite common. This plant communityis located primarily in heavy clay soils on gently rolling hills and valleys throughout the Planning Area. Grasslands have been subject to many man-made constraints and pressures including competition from introduced non-native species, agricultural conversion and urbanization. In areas where the grasslands have remained, this has resulted in the replacement of the native bunch grasses with introduced non-native grasses. This community is becoming increasingly scarce in Southern California.
Oak Woodland / Oak Savannah
Oak woodland communities occur in canyon bottoms and north-facing hillsides, often as a fairly dense growth of coast live oak with associated species such as poison oak and toyon. Valley oak, on the other hand, usually forms a savannah comprising large widely-spaced trees separated by extensive grasslands. This plant community is present within the Planning Area but in its undisturbed form is limited to small geographical areas. Oak woodlands and savannahs support a wide variety of bird and animal species wherever they occur. Oak woodlands and savannahs primarily occur in gently rolling foothills and valleys. As a result, urbanization of these areas throughout Southern California has resulted in decline in the range of this once wide-spread plant community. For example, most of the Conejo Valley was once an extensive oak savannah. While the City’s Oak Tree Ordinance has enabled many of these historic oaks to be preserved as development took place, the only remaining examples of this natural landscape are within public open space.
This plant community is restricted for the most part to perennial streams or springs where there is moisture at or near the surface much of the year. In valleys and canyons where Riparian vegetation naturally occurs, this plant community provides important habitat for wildlife, yet it is diminishing throughout the Santa Monica Mountains region and comprises less than three percent of the Planning Area’s remaining natural open space. In Southern California, the majority of remaining riparian woodlands are largely confined to remote inaccessible areas. Urban development and associated flood control projects have been the principal causes for its loss both locally and regionally. Within the Planning Area, riparian plant communities occur in two general forms: riparian woodland and herbaceous riparian. Riparian woodland consists of an overstory of large deciduous trees such as white alder, California sycamore and Fremont cottonwood with an understory of shrubs such as California wild rose and mule fat. Herbaceous riparian comprises a dense growth of low perennial plants such as iris-leaved rush, sedges and California loosestrife.