In 2006, the famed LA palm trees were begining to die in noticable numbers. The Palms were contracting bateria diseases from the soil.  Though not all Palms are dying, the foresty department of LA is trying to control the situation. The plan then, by the LA Recreation and Park Departments, was to concentrate on planting more native trees instead.   So, here is some information about the these new/old trees that you might be notcing in your community parks and neighborhoods.The following information was taken from the Urban Forestry Division.

Coast Live Oak (Quercus agrifolia)

 

The Coast Live Oak is the premier native tree species in the City of Los Angeles . Coast Live Oaks are found predominately in the Santa Monica Mountain range. They often grow on the northern and eastern facing areas where the summers afternoon sun is not as intense but they may be found all over the range. For the most part, these trees are not found naturally occurring in the valley floor or basin of the City.

 

Coast Live Oak trees are evergreen, long-lived, and naturally occur in both single and multi-trunk form. These trees are commonly found in groups and actually comprise the main flora of what is termed an Oak Woodland. Coast Live Oak trees can grow to heights of sixty feet or more and spread to nearly one hundred feet. The trees are extremely well adapted to the California climate and very tolerant of drought. In fact, if their native dry environment is changed and heavy irrigation is applied, it is not unusual for these trees to become stressed, acquire fungal pests, and even die. Coast Live Oak are truly one of the City’s most valuable natural resources. Therefore, they have been included in the City’s Protected Tree Ordinance.

 

Valley Oak (Quercus agrifolia)

 

A close relative of the Coast Live Oak, the Valley Oak is truly a spectacular tree. Valley Oaks can reach eighty to one hundred feet and have a canopy approaching the same. Valley Oak trees are deciduous and more open canopied than their cousins. A single- trunk tree, the trunk can often exceed sixty inches in diameter. Specimens one hundred years old are still in their infancy as the trees can live four to five hundred years.

 

Valley Oak trees are loners and referred to as a solitary species although their often are several trees growing in the same general area. Unlike the Coast Live Oak, they almost never grow close enough to intermingle canopy with their brethren. These trees are amazingly drought tolerant and are often, as their name implies, in the valleys and flat areas of the City. The number of Valley Oak trees has been severely diminished and there are not large numbers of these trees remaining in the City and for the most part are found in the San Fernando Valley.

Western ( California ) Sycamore (Platanus racemosa)

 

The California Sycamore is native tree species of the City’s stream and creek beds (riparian). California Sycamore is deciduous and can be found growing naturally to heights approaching one hundred feet. These trees grow in single and multi-trunk form and can be found growing nearly parallel to the ground for many feet or tall and straight reaching for the sky.

 

Although naturally occurring near waterbeds, California Sycamore are affected by several fungal pests that is more pronounced near the coast. These trees perform better when they are just outside of the coastal marine layer daily influence. The leaves of these trees are covered with fine “hair” and the fruit when dry can burst into fine individual seeds both of which can be irritating to the lungs when inhaled. Nevertheless, the California Sycamore is truly a beautiful and successful City native tree species.

 

California Black Walnut (Juglans californica)           

 

The California Black Walnut is found most often growing as a part of the Oak Woodland ecosystem. Unlike the other protected tree species, this tree does not reach great height and is most often found in a multi-trunk form. Typically the California Black Walnut contains several trunks reaching twenty to twenty-five feet. This species is deciduous and bears an edible fruit although the fruit is small and can be tough to extricate from its covering and shell.

 

The California Black Walnut is a tough tree that even when cut down to a stump often re-grows. The leaves, bark, and fruit debris are toxic to other plants and it is not unusual to find the area under the trees canopy completely devoid of other plant life. Like the Coast Live Oak, the California Black Walnut is extremely drought tolerant and does not like to be too wet.

 

California Bay (Umbellularia californica)

 

The California Bay tree is an evergreen tree that can reach sixty-five feet in height with a somewhat columnar form. Although it does not mind a fairly wet growing area, it is also very tolerant of drought. It is found for the most part within the Santa Monica Mountain range. This tree is relatively long-lived, approximately one hundred fifty years, but not in comparison to the native Oak species.

 

The California Bay is often contained within the Oak Woodland ecosystem. Its leaves, although not as popular as its relative Grecian Laurel, were used extensively by the indigenous Indian population in soups and stews.

 

for more info: http://lacity.org/boss/urban%20forestry%20division/index_calibay.htm