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Castro Valley, CA 94546

Tax ID# 94-2797523

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Marshall Elementary School

20111 Marshall Street, Castro Valley, CA

Marshall has a great campus with lots of interesting features. We have divided them into three areas.

1. The Big Rocks

The Big Rock Area has some wonderful boulders. They provide a great opportunity to look at what lies under our feet, including the rocks and soil. There are also several nice examples of two native California oaks and a tree that looks like a pine but isn't.

1. Graywacke Sandstone Boulders

Much of Castro Valley stands on sandstone, and outcrops of it can be found throughout the area. Since most sand is made of quartz, sandstone is mostly quartz. Other “impurities,” such as clay, hematite, ilmenite, feldspar, and mica, add color to the sandstone. Iron compounds can make sandstone tan or brown. Sandstones with more impurities are called wacke or graywacke. Sandstone is a sedimentary rock formed from (not surprisingly) grains of sand (0.0625 to 2 mm in size). For example, over time, the sand in an old river delta or ancient beach becomes stuck together by much finer particles of quartz, calcium carbonate or iron oxide, sometimes produced from volcanic ash. An outcrop of sandstone can tell us a lot about geologic history, but typically few fossils are found in sandstone.

2. Dirt and Soil

Soil is easy to overlook. It’s common as, well, dirt. But soil isn’t just dirt. Soil is made up of many things. Most of it is minerals, broken up rock, clay, and sand. The key element is broken down living material, which comes mostly from decayed plant material. Living plants get their nutrients from the recycled plant and animal material and from the minerals in the soil.  

3. Grassy Field.

The grassy lawn is not exactly a native California feature, but it is now its own environment. The grass is mostly Kentucky bluegrass (Poa pratensis) and fescue (Festuca sp.) with some crabgrass here and there.

4. Blue and Coast Live Oaks

Coast live oak (Querqus agrifolia). (right) Several trees can be seen along the fenceline. This California native, evergreen tree has a short stout trunk and many crooked branches. It grows to a height of about 80 feet. The acorns have a thin egg shape and are an inch or so long and were preferred by the local Native Americans. They  removed the shells and ground the nut into meal. Then they washed them to remove their bitter taste and boiled or baked them for food.

Blue oak (Querque douglasii). (left) The blue is a native California tree. Its simple alternate leaves have a waxy coating that helps them retain water. They are about 1-3 inches long with wavy margins and somewhat blue-green from above and more yellow-green on the bottom. The trees grow in a twisted manner that makes them less desirable for lumber. They also grow very slowly. Native Americans used them acorns as food.

5. Casuarina Trees (Casuarina cunninghamiana)

They may look like pine trees, but they are not. Originally from Australia and Polynesia, they are now planted as ornementals. Casuarina trees grow to about 60 feet. Their slender branches look a lot like pine needles. However, the leaves of the casuarina appear as small scales at the nodes on the branches.

6. Palm Tree Stump

The stump is left from a palm tree. It is a mass of fiberous material. Compare this tree stump to the one in the Front Yard Area.

7. Other Plants Several other plants are found around the big rocks.

 Arborvitae (Thuja orientalis). Arborvitae is a common ornamental. It is a member of the cypress family. It has small (1/2 inch) cones at the ends of short twigs. The leaves this family are a rich source of vitamin C and were used by Native Americans and early explorers to prevent scurvy, a disease resulting from a lack of vitamin C.

 Privet (Ligustrum sp.) is widely used as a hedge and is in the olive family. The very small flowers appear in bunches. A dark-colored fruit is a favorite of birds, but poisonous to humans.

 Laurel (Umbellularia californica). This native of western North America, is similar to the bay laurel, whose leaves are used in cooking.

2. The Front Yard

The area at the front of Marshall School has excellent examples of different kinds of trees that illustrate the differences between cone-bearing conifers and deciduous trees that flower and drop their leaves in the fall. There are also trees typical of the drier areas of California with their small waxy leaves and of Eastern broadleaf deciduous trees. The ginkgo, in the planters between the buildings, is yet another type of tree. 

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1. Different kinds of trees

Conifers and Deciduous trees. Trees have evolved many strategies to survive, and some of these can easily be seen in the park. First, conifers, such as pines, spruces, and redwoods, are all conifers. They do not lose their leaves in the winter. They do not have flowers. Deciduous trees have flowers and lose their leaves in winter.

Magnolia The magnolia blooms in early spring before the leaves come out. The flowers grow at the end of the branches. Magnolia flowers evolved a long time ago, and they are similar to the very first flowers. Some of the oldest fossil flowers discovered are similar to magnolia blossoms. They are primitive features for several reasons. They have many stamens and pistils, which are parts of the flower. The stamens are arranged in spiraling rows, and both stamens and pistils are attached to a fingerlike receptacle.

Deodora (Cedrus deodora). Several trees are near the corner of the park. The deodora is in the cedar family. These are large trees that are shaped like pyramids. The trees grow to about 80 feet. Cones of 3-4 inches are found on the lower branches through the winter months. These trees were originally native to the Himalayas, but now are common decorative trees.

Coyote Bush (Baccharis pilularis). Several plants are in this corner of the park. Baccharis comes from a Greek word for plants with fragrant roots, and pilularis refers to the sticky resin on its flowers. Coyote brush, a common native California plant, adapts its shape to its environment. Near the seashore, it is low to the ground. In places where it is more protected, coyote brush forms bushes. Its leaves have a waxy coating to reduce water loss, and the coating also protects them from fire. The coyote brush sends out a very large root system to find water.

2. Sedge (family Cyperaceae)

This family contains a large number of plants that look a lot like grass. In general, they prefer to grow in wet areas, so if you see one, it's a good guess that there is water nearby. The ancient Egyptians used one of the sedges to make papyrus for writing.

3. Two kinds of Birch Trees

River birch (Betula nigra) (pictured with the magnolia above) is also called the black birch. Like all birches, its bark peels away from the trunk and branches. In the river birch, the inner bark is dark.

White birch (Betula papyrifera) (left) is a medium-sized deciduous tree and a native of North America. A lot of butterflies feed on the white birch. The bark is filled with resin and was used by Native Americans on the outside of canoes to waterproof them.

4. California Ground Squirrels  (Spermophilus beecheyi)

The piles of dirt indicate that we have company here. California ground squirrels, (they aren’t really gophers) are common throughout California and the western United States. They are gray and light brown with buff or grayish yellow undersides. They are about 12-18 inches long with a 6-inch tail. In the spring, a mating couple will produce a single litter of 5-8 babies.

Because they dig up yards and gardens, ground squirrels are looked upon as a pest, Also they eat the leaves, flowers, roots, and seeds, and fruits. They are very shy, but if you sit quietly for a while, you might see one peeking out of his hole. Enjoy looking at them if you are lucky enough to see them. But like with all wild animals, it’s best to stay away from them.

5. Tree stump

Tree stumps are fascinating. You can easily see the tree rings, which provide a record of local climate during the life of the tree. Many trees are hundreds of years old, and a few live thousands of years. Thus, the rings provide information that is not available from scientific records.

At the center of a stump is a small core of pith formed when the tree was a sapling. Then comes a cylinder of dark dense wood -- the heartwood -- with annual rings which are often very narrow near the core because as a youngster it grew in the shade of older trees and did not get enough light. Surrounding that is a collar of lighter-colored wood -- the sapwood -- with a smaller number of rings. Beyond that and just inside the rough outer bark is a spongy layer of inner bark called the phloem.

The most important part is hard to see because it is so small. Between the sapwood and the inner bark is a single layer of living cells called the cambium, which has the magical property of producing, each year, a layer of sapwood on the inside and a layer of inner bark on the outside. The wood formed each spring consists of light-colored thin-walled cells. Near the end of summer, the cells are smaller with darker walls. Together, the springwood and summerwood form a ring.

6. Small trees in the corner

Silk Oak (Grevillea robusta). This "oak" is not an oak at all. It is an evergreen tree with fern-shaped leaves that are dark green on top and silky white underneath. This native of Australia is used as an ornamental plant in the US.

Acacia (Acacia sp.). Acacias are in the pea family. The seed pods resemble pea pods. The leaves of acacias are compound pinnate. That means that each leaf contains a large number of smaller leaflets. There are roughly 1300 species worldwide. In the US, the tree is mostly grown as an ornamental. They are sometimes confused with locust or mimosa trees, which have similar features.

Redwood (Sequoia sempervirens). The redwood is the world’s tallest tree. The tallest known specimen is 368 feet, but typically, they reach 200 feet or so. The trunk is reddish brown and much tapers from a very thick bottom to a thinner top. Sprouts grow from stumps, and in redwood forests, you can usually find circles of redwoods that that have grown up from the remains of the original tree. This is a very important tree for lumber.

3. The Lower Field Area

1. Pines. Two kinds of pine trees can be seen along the fence.

Monterey Pine (Pinus radiata). The Monterey pine is common in California. It grows to about 100 feet. Its branches point upward and it has a round top. The bright green needles occur in clusters of three and are 2-4 inches long with a blunt tip. Cones are 3-5 inches long. The dark grey to brown bark is quite fissured. The Monterey pine in California is seriously threatened by an introduced fungal disease called pine pitch canker.

 Aleppo Pine (Pinus halepensis) . This pine comes originally from the Mediterranean area, but is often planted in California because of its heat and drought tolerance is valued. This small to medium-size tree will grow to 70 feet. The bark is orange-red, thick and deeply fissured at the base of the trunk, and thin and flaky in the upper crown. The very slender needles occur in pairs and are 2-3 inches long. Although the cones open over several years, they will open quickly after a forest fire.

2. Pine cones

Pine trees and other conifers do not have flowers or fruits. Their seeds are contained in cones, and the cones are male or female. The one that we normally think of as a “cone” is the female cone that produces the seeds. The female cone are very helpful for identifying the species of conifers. Female cones contain the ovules, which when fertilized with the pollen, become the seeds.

 The pollen comes from the smaller male cones. After fertilization, most pine seeds mature in 18-24 months. Younger cones are green in color and become brown in the second year. When the cones mature and dry out, seeds are released.

 Male and female cones are found on the same tree. Female cones are usually closer to the top and grown as individuals. Male cones sometimes grow as clusters. Also male cones grow at the base of a branch, and female cones grow at the tip.

3. Poplar (Populus sp.)

Poplars are deciduous trees and lose their leaves in the fall. The broad leaves indicate that this is not a native California tree. Poplar is a fairly soft, but good quality wood that is used in furniture makiing and sometimes in flooring.

4. Evergreen Ash and its roots along the ground

 (Fraxinus sp.). Ashes are mostly deciduous trees, but a some specifics such as this tree retain their leaves all year. This specific tree is very old and particular large. Most ashes have excellent fine-grained lumber. The common name "ash" is taken from the Old English word æsc, which referred to a spears that were made of ash wood.

Tree roots. Visible on the ground below are roots running in every direction. Tree roots cover a lot of area. The roots of Southern magnolias spread out nearly four times the diameter of the leaf crown. On average, tree roots spread about three times further than the dripline (a line enclosing all of the branches). In other words, a tree with a 10-foot spread of branches would have a root area 30 feet in diameter. Every tree species has its own type of root system. Some oaks frequently develop tap roots; maples often do not. The arrangement of roots for any specific tree, however, will be determined by a variety of factors, such as the type and compaction of the soil and availability of water.

5. Pistachio (Pistacia vera)

The pistachio is a small tree originally from central and southwestern Asia. It has deciduous pinnate leaves. Like the almond, its fruit is a not a true nut, but certainly looks like one. The “nuts” come in a whitish shell and have a light green color and a characteristic flavor. The tree here is technically not on the campus, but it’s just too good to pass up as a natural feature.

6. Hackberry (Celtis sp.)

This medium-size deciduous tree has pointed and serrated leaves that are 1-5 inches long. The fruit is a small drupe (cherry-like) fruit that is dry, but sweet. But remember: Do not eat anything that you find outside.

7. Coast Oak and Arborvitae

Coast Oak (Querqus agrifolia). (right) Several trees can be seen along the fenceline. This California native, evergreen tree has a short stout trunk and many crooked branches. It grows to a height of about 80 feet. The acorns have a thin egg shape and are an inch or so long and were preferred by the local Native Americans. They  removed the shells and ground the nut into meal. Then they washed them to remove their bitter taste and boiled or baked them for food.

 Arborvitae (Thuja orientalis). Arborvitae is a common ornamental. It is a member of the cypress family. It has small (1/2 inch) cones at the ends of short twigs. The leaves this family are a rich source of vitamin C and were used by Native Americans and early explorers to prevent scurvy, a disease resulting from a lack of vitamin C.

8. Date Palm (Phoenix dactylifera)

The date palm is extensively cultivated for its edible fruit. However, this particular example is a male and bears no fruit. These medium-sized trees often clump together with several trunks from a single root system or growing singly. We eat the seed or dates.