The Puente Hills contains several distinct ecosystems, or collections of distinct plants and animals interacting together. The Riparian Community is found in canyon bottoms and contains large trees (sycamores, oaks, willows). The plants here are similar to those found back east in that rather than drought being the main factor in their growth, it is cold. Canyon bottoms are colder than the surrounding hillsides because cold air is heavier than warm air and thus by gravity settles to the lowest places and flows like water down the canyons. Plants here must deal with this chilly air and one way is to drop the leaves during the winter. The sycamores and cottonwoods do this and give us a taste of Eastern fall color! The Coastal Sage Scrub Community is found on the slopes and is home to many aromatic and drought tolerant shrubs such as California sagebrush and several mint family members. This is an inceasingly less common community because it grows in places where people want to live. Many plants here go dormant during the dry season to avoid water loss. By dropping the leaves, plants reduce water vapor loss since openings in the leaves called stomata allow moisture to leave during photosynthesis. Fewer leaves, less water "leaks" to the air. During spring, this community has some of the most beautiful flowers you will ever see. A drive up Turnbull Canyon Road will give a great introduction to these plants. Toyon/Sumac Chaparral is found on the north facing slopes and is covered by plants that are evergreen, tall shrubs. These plants have large leaves and approach tree size. North facing slopes are moister than south facing slopes since the sun is always to our south so these slopes are shadier and cooler. Plants here don't have to be as drought tolerant as drier communities so they can afford the more luxurient growth. Sumac is very frost sensitive and burns easily in cold weather, showing that the cold air does sink to the canyon bottoms from the hillsides. Annual Grassland Communities also occur on the slopes and are either natural or the result of past overgrazing by domestic cattle. The plants are mostly annual but some perenniels do occur. Recently, two native bunchgrasses, Nasella pulchra and Nasella lepida, were found in turnbull Canyon and other places within the Puente Hills which is significant since Valley Grassland is an endangered ecosystem and qualifies an area for special consideration! A large native grass, up to seven feet in height, called Giant Wildrye grows here and mixed in other communities. In one area of Turnbull Canyon it is so thick and dominant that I call the area Wildrye grassland! Southern Oak Woodland occurs in the canyon bottoms or on the north facing slopes. Many old and large spectacular Coast Live Oaks grow here as they have for thousands of years. These trees have deep roots and survive drought by reaching underground water reserves. They are evergreen and the acorns are food for many animals. The trees can grow either as islands in another community or in thick forests as the dominant plant. These are very beautiful trees and give a year round green to a sometimes brown world. Walnut Woodlands occur in the same habitats as oak woodland but have Southern California Black Walnuts as their indicator trees. These are deciduous trees with somewhat fern-like leaves. The walnuts they produce taste just like the store bought ones but stronger. the leaves turn gold in the fall and are lovely to see. This community, like the coastal sage community, is becoming rarer so all efforts to preserve areas such as these are vital. Southern Cactus Scrub occurs on south-facing slopes either among other communities or in almost pure stands. The major plant here is Prickly Pear, a cactus with large, flat pads and sweet, red fruits (if you can get past the thorns!). These communities are plentiful in the Puente Hills in the reserves listed under favorite areas. Please visit these beautiful natural areas and enjoy the peace and adventure they have to offer! See ya on the trails!