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4th & 5th Grade

School garden-science lessons on this page help develop science-based, eco-literacy in 4th & 5th grade students.

February 22nd - Monoculture Farming

Use the arrows in the upper left hand corner of the video to move around the farm.

February 1st - Case Study: Eucalyptus

Eucalyptus: How California’s Most Hated Tree Took Root

Blue gum eucalyptus globulus grows fast and in poor soil, which made it a favorite of investors anticipating a hardwood famine in the early 1900s. (Samantha Shanahan/KQED)

Depending on whom you ask, eucalyptus trees are either an icon in California or a fire-prone scourge.

Bay Curious heard from two hikers wanting to know about the past and future of California’s eucalyptus trees.

“How did all of this eucalyptus get to the Bay Area?” asked Christian Wagner, a tech worker who lives in Pleasanton.

“I know that they’re invasive, so what do we do about that? Are they worth keeping around? Or do we need to get rid of them and replace them with something else?” wondered Julie Bergen, an occupational therapist from Alameda.

Reaching heights of more than 100 feet, the main kind of eucalyptus you’re likely to see here is Tasmanian blue gum, eucalyptus globulus. They feature sickle-shaped leaves hanging from high branches, and deciduous bark that is forever peeling from their shaggy trunks. Some people experience the smell of eucalyptus as medicinal; others say the trees just smell like California.

The trees are deciduous, shedding their bark every year.
The trees are deciduous, shedding their bark every year. (Samantha Shanahan/KQED)

So how did eucalyptus trees get here?

“They came here as envelopes of seeds on boats coming to California in the 1850s,” explains Jared Farmer, author of “Trees In Paradise: A California History.”

During the Gold Rush, Australians were among the throngs flocking to a place where wood was in short supply.

The predominantly Australian eucalyptus genus includes more than 700 species, ranging from tall trees to shrubs. Hundreds have been tried out in California, but only red gum and blue gum reproduce on their own here.

“This was the era of wood power,” Farmer says. “Wood was used for almost everything. For energy, of course, but also for building every city, for moving things around, all the things where today we use concrete and plastic and steel.”

Besides the practical need to plant more trees, settlers who were used to dense forests also felt that the lack of trees in California’s grassy, marshy, scrubby landscape made it feel incomplete. So within a few years, nurseries in San Francisco were selling young eucalyptus grown from seed.

The trees grew remarkably quickly here, even in poor soil.

“In an average rainfall year here in California, these trees probably put on 4 to 6 feet in height and maybe, in their early growth years, a half-inch to an inch in diameter,” says Joe McBride, a UC Berkeley professor emeritus of landscape architecture and environmental planning.

Beyond the drive to change the landscape and provide firewood, Californians also planted eucalyptus (mainly blue gum) to serve as windbreaks.

Eucalyptus trees grow fast, sometimes putting on four to six feet in height in a single year.
Eucalyptus trees grow fast, sometimes putting on 4 to 6 feet in height in a single year. (Samantha Shanahan/KQED)

In fact, that was the original purpose of what’s now the largest, densest stand of blue gum eucalyptus in the world, on campus at Berkeley, says McBride. It was planted around 140 years ago to provide a windbreak for an old cinder running track — to keep its fine ashen gravel from blowing into athletes’ faces.

The trees’ success in California owed to a lack of enemies here. Because they were grown from seed, they hadn’t brought along any of the pests or pathogens (or koalas) they contend with back in Australia.

An early 20th century boom

Within a few decades of its arrival, many Californians grew disenchanted with eucalyptus. Blue gum proved terrible for woodworking — the wood often split and cracked, making it a poor choice for railroad ties. The trees also proved thirsty enough to drain nearby wells.

“If you go back to California farm journals of the 1870s, ’80s, ’90s, there’s just report after report of disappointment, like ‘these trees are no good,’ ” says Farmer, the historian.

But things changed in the early 20th century when U.S. Forest Service officials grew concerned about a looming timber famine. They feared forests in the eastern United States had been overexploited and wouldn’t grow back, and predicted the supply of hardwood would dwindle over the next 15 years.

The bark sheds often, peeling in large strips.
The bark sheds often, peeling in large strips. (Samantha Shanahan/KQED)

Investors saw an opportunity: California had a tree capable of growing to full size within that time frame. If hardwood was about to be scarce, they reasoned, such trees could be in high demand and yield sizable returns within a few short years. (These people, Farmer says, were not reading blue gum’s lousy reviews in old farm reports. “And even if they did read them, maybe they wouldn’t care because they just wanted to make a buck; they were just flipping land.”)

This played out as a speculative frenzy — a bubble. Boosters began selling plantations dense with eucalyptus — hundreds of trees per acre. Farmer writes in his book that claims were made like: “Forests Grown While You Wait,” and “Absolute Security and Absolute Certainty.” In just a few years, millions of blue gums were planted from Southern California up to Mendocino.

The anticipated timber famine never came to pass. Forests further east proved more resilient than expected, and the need was offset by concrete, steel and imports, like mahogany. Ultimately, the thousands of acres of eucalyptus planted around California were not even worth cutting down. Much of what you see today is a century-old abandoned crop.

What’s fire got to do with it?

Eucalyptus trees have lovers and haters in California. A big part of the debate over whether the trees should be allowed to persist here traces back to the East Bay firestorm of 1991, which left 25 people dead and thousands homeless. Vast swaths of eucalyptus burned.

“People at the time, I don’t think, associated that with a planted plantation; it was just a eucalyptus forest,” says CalPoly botanist Jenn Yost. “And then when the fire came through — I mean that fire came through so fast and so hot and so many people lost their homes that it was a natural reaction to hate blue gums at that point.”

Because the trees shed so much bark, critics argue they worsen the fire hazard and should be cut down. Defenders point out California’s native plants also have a tendency to burn. Both say the science is on their side, but so far no landmark study has shut down the dispute.

That ongoing dispute is also politically entrenched. A few years ago, federal funding to cut down trees in the East Bay hills was rescinded, after protesters got naked and hugged the eucalyptus trees on campus at Cal.

To some, the scent of eucalyptus trees is simply the scent of California.
To some, the scent of eucalyptus trees is simply the scent of California. (Samantha Shanahan/KQED)

Are they here to stay?

Blue gums can’t reproduce on their own just anywhere in California; Yost says they need year-round moisture. They’re able to regenerate in places like California’s coastal fog belt, but elsewhere “there are some plantations that don’t reproduce at all. When you go there, the trees are all in their rows, there’s few saplings anywhere to be seen, and those trees are just getting older.”

Not all non-native plants capable of reproducing on their own do it enough to have an ecological impact, Yost says.

“As soon as it starts outcompeting native species or fundamentally changing the environment so that native species can’t grow there, we would consider that an invasive species,” she says.

Blue gum is classified as a “moderate” invasive, putting it a tier below such uncharismatic weeds as yellow star-thistle and medusahead. McBride, the retired Berkeley professor, says “although there’s been marginal expansion of some eucalyptus stands, it’s really not well adapted for long-distance dispersal. It hasn’t really spread very much on its own.”

With an estimated 40,000 of eucalyptus planted across the state, the trees aren’t easy to get rid of. Slicing down a large blue gum near a building can require a crane, at an expense of thousands of dollars. And keeping them from resprouting can also be its own chore.

Long term, as the climate changes over the coming decades, it’s possible the aging eucalyptus groves that don’t get enough water to reproduce will begin to die.

Then again, if the state becomes hotter and drier, it may become the type of place where some Australian species are able to thrive.



Bay Curious PodcastBay Curious is a podcast that answers your questions about the Bay Area. Subscribe on Apple PodcastsNPR One or your favorite podcast platform.

by Diana & Kristin (aka Appetite for Geographics)
University of San Francisco
May 5, 2018


Angel Island is a small island located approximately 1 mile southeast of Marin County’s Tiburon Peninsula in California’s San Francisco Bay Area. The island is approximately 1.18 miles squared and is currently managed by the Golden Gate National Recreation Area, of GOGA for short (Office of Historic Preservation). The island has a diverse variety of flora and fauna across various ecological zones. Throughout its history, Angel Island has been used for a variety of purposes, including military forts, a US Public Health Service Quarantine Station, and a US Bureau of Immigration inspection and detention facility (NPS). Because of this human interference, several types of non-native tree species have been introduced to the island, specifically Tasmanian blue gum eucalyptus (Eucalyptus globulus). There is also a large population of native tree species in this area, one major species being coast live oak (Quercus agrifolia). Both species can be viewed to have positive and/or negative effects on the surrounding ecosystem, which is summarized below. The effects can put a constraint on the health of the entire island, as seen through biodiversity and abundance of the understory.

Amidst local media coverage and controversy, in the 1980s California State Parks undertook environmental actions to remove most of the eucalyptus from the island, in order to restore native flora and reduce fire danger. By 1997, 80 acres of Tasmanian blue gum eucalyptus were removed, and nursery-grown native plants were planted in the cleared areas. Six acres of historically significant eucalyptus trees were retained, and active restoration work continues on the sites where trees were removed (D. Boyd). According to GOGA, the 10-year restoration work costed more than $US 480,000 (NPS). Without active eucalyptus management, Angel Island can become overgrown, its biological diversity damaged, and the potential for wildfires can increase, making it crucial to have ongoing evaluation of any restoration work to determine the success rate (NPS). Since eucalyptus management is also highly technical, costly, and dangerous, the aim of this project is to make suggestions to the Golden Gate National Recreation Area on how they can update any current or future native ecosystem restoration work on the island.

The scope of this project is to analyze the effects, positive or negative, non-native Tasmanian blue gum eucalyptus (Eucalyptus globulus) has on the native vegetation in the understory on Angel Island in the San Francisco Bay Area and compare it to the understory located beneath native coast live oak (Quercus agrifolia) canopy cover. This project will also determine the abundance of species types under each canopy cover and if soil types are a factor in each canopy cover type.

<strong>Every October, thousands of butterflies make a stop in a Pacific Grove eucalyptus grove, the preferred Monarch butterfly habitat, during their migration to warmer climates. The butterflies hang in clusters from eucalyptus branches to maintain body temperature, and the resulting effect is stunning. Visitors come from miles around to take Monarch butterfly tours throughout the sanctuary.</strong>

<strong>The Monarch butterflies that come to Monterey County are a special generation of butterfly. While most Monarchs live only four to five weeks after they reach adulthood, the generation that overwinters in Monterey County lives up to six months. Even more incredible, scientists still aren’t sure how each new migrating generation knows the way to warm weather spots. This stunning display is best viewed at the Pacific Grove’s Monarch Grove Butterfly Sanctuary.</strong>

Pinole Point Trail to Giant Station Trail, Point Pinole Regional Shoreline
Length: 4.13-mile loop, Intensity: easy
This trail brings you right into the park’s most vibrant eucalyptus woods, offering an aromatic experience you won’t forget. San Pablo Bay is typically breezy, making Point Pinole a perfect recreational site on a hot day.

Bull Valley Trail Loop, Carquinez Strait Regional Shoreline
Length: 4.8-mile loop, Intensity: moderate
From the blue waters of Carquinez Strait to the north, to the rolling hills in the south, this park offers magnificent views. The trail traverses open grasslands and small eucalyptus groves that provide welcome shade on a sunny day and, at the midway point, takes you through the historic town of Port Costa.

Kennedy Grove Recreational Site
Planted in 1910, the Kennedy Grove eucalyptus trees offer a fragrant, calm setting for relaxing and enjoying nature. The centrally located turf meadow provides additional play space for picnickers with enough room to toss a Frisbee.


Pinole Point

January 18th - Plant Adaptations

Plat the Plant Adaptation Game!

2 Players

Goal: Collect sets of cards that pertain to plants found within a particular biome. The card set will show specific adaptations of different plants that help them survive in that biome.


  1. Shuffle cards and deal each player eight cards. Place the rest of the cards in a stack face down in the middle of the table, with one card face up to start the game.
  2. Each player looks at his/her cards. The goal is to collect all four cards from two different biomes.
  3. The first player can choose the card that is face up on the table or draw one card from the deck and puts it in his/her hand. The player will then select one card to discard and will place it face-up by the pile of cards that are face-down.
  4. The next player can choose the previously discarded face-up card on the table or draw a new card from the face-down stack.
  5. Play continues until a player has collected all four cards from two different biomes.
November 30th - Plant Vascular System
November 16th - Root Systems

To make a monocot root cross-section diagram, you will need paper, pencil and, if you have one, a compass. Make sure your label your drawing. The internal structure of a monocot root like maize, rice, wheat etc. has the following tissue;

1. Epidermis: The epidermis or outermost layer of the root is known as rhizodermis. Root hairs in epidermis absorb water and minerals salt.

2. Cortex: The cortex lies below the epidermis. It help in conduction of water and minerals salts from root hairs to inner tissues and storage of food.

3. Endodermis: It is innermost layer of cortex and regulates flow of fluid both inward and outward.

4. Stele: It consists of pericycle and vascular tissues where pericycle lies just below the endodermis.

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