Self-Guided Tree Walk: Jr. Museum and Zoo

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This Tree Walk begins outside the front entrance to the Palo Alto Junior Museum & Zoo, 1451 Middlefield Road.

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1. Maidenhair Tree (Ginkgo biloba)

This tree to the left of the entrance to the Palo Alto Junior Museum has a unique leaf shape and it turns a gorgeous golden yellow in the fall. Because the leaves fall nearly all at once, they create a carpet of color beneath the tree. Maidenhair Trees have been around for a very long time. Some fossilized gingko leaves have been dated to 270 million years ago – the time when dinosaurs still roamed the earth, hence it is nicknamed "Dinosaur Tree."

2. Pecan (Carya illinoinensis)

To the left of the Maidenhair Tree is a huge example of a tree that is rare in the Bay Area. Pecans are more common in the south-central U.S., where nuts drop from the tree in the fall. The nuts don't ripen properly here because the climate is too cool. A long stem with 11-17 opposite leaflets makes up a large single leaf called a compound leaf.

3. Water Gum (Tristaniopsis laurina)

Growing in a parking lot divider, this Australian native is a nice choice for an evergreen tree reaching less than 20'. It is a slow-growing relative of the eucalyptus and can take the form of a small tree, a tall screen, or a shrubby bush. It has peeling bark, clusters of small yellow flowers in late spring, and ¼" seedpods that resemble eucalyptus seedpods.

4. Coast Live Oak (Quercus agrifolia)

This tree at the southwest corner behind the Girl Scout House gets its name because it grows naturally primarily along the Pacific coast of California. Locally, it was probably the most common tree in the non-creek areas of Palo Alto when the Ohlone Indians lived here. They relied on the acorns of oak trees as a major source of food. Coast Live Oaks are one of two types of oak trees that are protected in Palo Alto; the other is the Valley Oak, Quercus lobata. Both of these trees are adapted to very little water in the summer and should not be irrigated during dry months.

5. Canary Island Date Palm (Phoenix canariensis)

Canary Island Date Palms can grow to 60'. The trunk is patterned with the bases of old leafstalks. The graceful, arching fronds form a crown that can be 50' wide.

6. Coast Redwood (Sequoia sempervirens)

Redwoods of many ages are along this path; the oldest is probably the one with the huge base nearest the fireplace of the Girl Scout House. In the coastal mountains they capture water out of fog; water drops then fall to the ground and provide moisture for the roots. Palo Alto is named for El Palo Alto (Spanish for "the tall tree"), a 1,000-year-old Coast Redwood near El Camino Real and San Francisquito Creek.

7. Chinese Elm (Ulmus parvifolia)

These beautiful, graceful trees surrounding the picnic area at the back of the Girl Scout House can be evergreen or deciduous, depending on temperatures. They grow rapidly to 40–60' with an equal or greater spread. Chinese Elms vary in shape, but usually appear spreading with long weeping branches that reach down to the ground if not pruned. They were extensively planted in Palo Alto as street trees, but the City no longer plants them because of the high cost of regular pruning and maintenance.

8. Sugar Maple (Acer saccharum)

Proceed northwest along the path to three Sugar Maple street trees on Hopkins Avenue. The sap of the Sugar Maple is used to make maple syrup in native eastern North America. This species can reach 60'. Its wood is used for furniture, basketball court floors, and bowling alley lanes, among other things. A maple leaf adorns the Canadian flag.

9. Valley Oak (Quercus lobata)

The street tree next to the Sugar Maples is a Valley Oak. Valley Oaks are native to this area. Like the Coast Live Oak, it is a protected tree in Palo Alto and a permit from the City is required for major pruning or removal. The leaves of Valley Oaks have rounded edges and drop to the ground in the fall. The botanists' term for trees that are leafless in winter is deciduous. Trees that have leaves all winter, like the Coast Live Oak, are called evergreen.

10. Chinese Pistache (Pistacia chinensis)

Two trees down from the Valley Oak, this tree shows the very spreading and symmetric form that the Chinese Pistache is known for. It has a compound leaf like the Pecan. Beautiful in the fall, the foliage becomes scarlet, orange, and sometimes yellow. These highly adaptable trees can tolerate lawn water or dry soil. They can grow to 30' with a 30' width and are a reliable street or lawn tree.

11. London Plane Tree (Platanus x acerifolia)

The next three street trees are London Plane Trees, a member of the sycamore family. London Planes are commonly planted as street trees all over the U.S. because they tolerates many soil types and stand up beautifully to the harsh urban environment. They tolerate drought well and may reach 80' by 40' wide.

12. Wilson Holly (Ilex x altaclerensis 'Wilsonii')

Continue walking along Hopkins Avenue to a small triangle-shaped tree next to the big pine. This evergreen is often a large shrub, but can be trained as a single-stemmed tree 15–20' tall, such as this one and another at the end of the Girl Scout House near Hopkins Avenue. It is one of the best hollies for warmer regions, including our area. With its 5" by 3" leathery leaves, it can make a good screen.

13. Aleppo Pine (Pinus halepensis)

This large pine has an open, irregular crown of many short branches reaching up. The light green needles are in bundles of two and 2½–4" long (pines always have needles in bundles). Native to the Mediterranean region, this pine is not a common landscape tree in this area.

14. Coast Redwood 'Aptos Blue' (Sequoia sempervirens 'Aptos Blue')

This young redwood is the cultivar 'Aptos Blue'. Like all young redwoods its branches go all the way to the ground to shade the trunk and retain moisture in the soil. This redwood cultivar has deep blue-green needles and branches that are more horizontal than other redwoods. It can be grown as a hedge for a tall screen, but it does require a lot of water.

15. Mock Orange (Pittosporum tobira)

Across the pathway from the Girl Scout House front door, Mock Orange is an ornamental landscaping plant common throughout the world. As it becomes older, it becomes a small tree. It blooms in April and May and has small white flowers with a fragrant orange blossom scent. It is native to Japan and drought tolerant.

16. Horse Chestnut (Aesculus hippocastanum)

Located in front of the Girl Scout House on the right side in a planting bed surrounded by pavement and growing next to the very common Southern Magnolia is an unusual tree for this area. It has a compound leaf with 5–7 leaflets arranged in a fan. Although a small old label on the tree says it is a Red Horse Chestnut, it is actually a Horse Chestnut. Horse Chestnuts are native to Europe, but closely related to our local native, the California Buckeye (Aesculus californica). When it blooms, its white flowers with red at the base are striking. Unlike true chestnuts, this tree's nuts are not edible.

17. Red Oak (Quercus rubra)

Cross the parking lots and enter a small forest to find an extraordinary specimen. This large leafy Red Oak has enormous reaching branches and beckons to be climbed. This tree is native to eastern North America, but it is planted widely in this area because it thrives in our climate. Its acorns are about an inch long, and the cup encloses only a quarter of the nut. The leaves turn a lovely red in the fall, and that is why it is called Red Oak.

18. Incense Cedar (Calocedrus decurrens)

The Incense part of the common name for these two somewhat leaning trees comes from the smell of the wood, which is used to make pencils. Incense Cedars are native to California and have thick bark that protects them from forest fires.

19. Deodar Cedar (Cedrus deodara)

These three Deodar Cedars have needles in bunches (not bundles, like pines) and branches that droop. The bunches of soft needles appear all around the branches and help distinguish it from its close relative, the Atlas Cedar (Cedrus atlantica 'Glauca', later on this walk). The cones on the tree always point up and sit on top of the graceful branches. This conifer is native to the Himalaya Mountains.

20. Red Horse Chestnut (Aesculus x carnea)

This planting area has several Red Horse Chestnuts, which you can recognize easily because each leaf is composed of 5 leaflets arranged in a fan. When in bloom in April, this tree has hundreds of soft pink to red flowers on plumes that point up. In summer, large seed capsules, the "horse chestnuts," form. This species can grow to 40'.

21. Port Orford Cedar (Chamaecyparis lawsoniana)

One large and two younger Port Orford Cedars at the end of the planting area look more like the Incense Cedars than the Deodar Cedars. The name Cedar is used for trees of several families. Port Orford Cedar and Incense Cedar are closely related to the cypress family, while the Deodar and Atlas Cedars are closely related to the pine family. The common name for the Port Orford Cedar comes from a town in Oregon near one of the only two areas where it grows naturally. The other area is on the Northern California coast.

22. Atlas Cedar (Cedrus atlantica 'Glauca')

The three largest trees in the planting area in front of the right side of the Junior Museum are Atlas Cedars. They are similar to the Deodar Cedars, but have shorter, stiffer needles and branches that don't droop. This tree is native to the Atlas Mountains of Algeria and Morocco. It needs a large area for full development and should not be crowded. Its wood is excellent for carpentry and has a strong scent that repels insects.

23. Dawn Redwood (Metasequoia glyptostroboides)

To the right of the entrance to the Junior Museum is a tree that resembles the Coast Redwood, but has softer leaves, is lighter green, and loses its leaves in the winter. This tree is an ancient tree – it was known to scientists only by its fossil record and was thought to be extinct. It was "rediscovered" in China in 1941 and the seedlings have been sent around the world ever since. This tree is approximately 60 years old.

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Trees protected by the City of Palo Alto tree ordinance

A permit is needed to remove or prune these trees.

Check the City of Palo Alto Tree Regulations.

Trees with low watering needs

These trees are best adapted to our climate and water availability.

Thirsty trees

These trees require frequent summer irrigation and will suffer from the drought cycle in our area.

Do not plant unless you are aware of a water source such as high water table or creek proximity.

Trees not recommended for planting

These trees are either invasive, do not perform well or create infrastructure or other problems.