Blue oak woodlands mixed with areas of foothill pine and grasslands are the predominant vegetation outside of the cultivated gardens of the monument and are what you see in the larger surrounding landscape of rolling hills and Tehachapi Mountains. In summer and fall - the dry seasons here - the grasslands have a golden color, but in winter and spring, rains turn the hills green, and wildflowers add spots or large splashes of color. In addition to the native plants that this area supports, there are also many non-native species introduced from other parts of the world. The grassland is primarily non-native annual grasses that were introduced to California during the mid-19th century and have subsequently become naturalized.
Trees with Character
The two native species of trees in the monument's oak woodlands both have character - they are interesting to look at and have adaptations that allow them to succeed in this relatively dry and periodically hot environment. The blue oaks are short with open, spreading canopies. The canopy is typically rounded with many crooked branches. The trees grow slowly and some individuals can reach 200 to 500 years of age. They can survive summers with weeks of temperatures exceeding 100º F. Their leaves are tough and thick to conserve water. In very dry, hot years, blue oaks may drop their leaves early and go dormant in the summer.
The other type of tree you will see on some of the dry rocky hilltops and slopes is the foothill pine (also known as gray pine for their grayish long needles). These pines grow on steep, dry slopes and rocky hilltops in the monument. They have the ability to grow on the poorest of soils using adaptations to regulate the amount of soil nutrients they uptake. These pines tower above the oaks and have foliage that looks wispy and scattered - not a good tree to stand under for shade! They have very large, heavy cones (6 to 10 inches long and weighing .75 to 2.2 pounds). The cone scales (with dagger-like points) hide many big, edible seeds, or pine nuts.
Tehachapi Mountains: A Convergence of Floristic Regions
Visitors to the area who want to explore the larger region can enjoy the plant diversity of the Tehachapi Mountains, where four floristic regions from the California and Desert Floristic Provinces - Sierra Nevada, Great Central Valley, Southwestern California, and Mojave Desert - converge. Plants from of each of these floristic regions can be found in the Tehachapis, and this range supports an impressive diversity of vegetation communities, including annual and perennial grasslands; coniferous and mixed hardwood-conifer forests; deciduous and live oak woodlands; pinon-juniper woodlands; Joshua tree woodlands; desert scrubs; and coast, desert, and montane chaparral shrublands. In some areas, you can find unique assemblages of species, such as valley oaks and Joshua trees growing side-by-side in desert-draining canyons on the southeast side of the Tehachapis.