Charles River Conservancy Learn and Discover Image

Learn and Discover: Charles River Plants

While walking along the Charles River, have you ever wondered about the types of flowers you see growing by the river’s edge? Have you ever been curious why some plants seem to dominate and take over entire banks of the river? Do you want to learn more about your local ecosystem?

Come explore the Charles River’s plants with us! Join us as we dive into the basics of the Charles River ecosystem, the native and invasive plants that live there, and how to get involved with your local ecology. Then, test what you learn with fun games!

INTRO: Getting Acquainted

To start, get acquainted with some of the beautiful plants we have in the Charles River parks by playing the game below! Flip through the images and find the matching pairs. Do you recognize any of the plants? Can you tell which ones are native or invasive? If you follow along with us, you’ll know what each of these plants are and how they fit into the Charles River ecosystem!

TOPIC ONE: What are Native and Invasive Plants?

Let’s start by learning about the different types of plants found in the Charles River parks, including native, invasive, and non-native plants! Once you’ve read through the information below, test your knowledge with the game!


Native plants are plants that are part of the balance of nature that has developed or evolved over hundreds or thousands of years in a particular region or ecosystem. Only plants found in this country before European settlement are considered to be native to the United States

An example that you might be familiar with from the Charles River Parks is the milkweed plant. This native plant forms balls of pink and purple flowers and provides key nutrients to the local monarch butterfly population


Invasive plants are plant species that are non-native or alien to a particular ecosystem and whose introduction causes or is likely to cause economic or environmental harm. These plants are able to grow quickly in many different areas and are capable of disrupting existing plant communities. 

An example of an invasive plant in the Charles River parks that you may know is Oriental bittersweet. This invasive climbing vine is easily recognizable by its yellow and red berries. It can quickly invade an area and form dense mats of vines that may smother trees and shrubs below.


Non-native plants are a third category and make up many of the plants with which you may be familiar. These are plants that are not native to their host ecosystem but are not harmful or damaging to that ecosystem either. While native plants are generally considered to be beneficial to an ecosystem and invasive plants are generally considered to be harmful, non-native plants are neutral forces in their ecosystem

A great example of a non-native plant in the Charles River Parks is the daffodil! While daffodils are originally from Europe and Northern Africa, they are not invasive because they don’t spread fast enough to cause harm to the other plants. The beloved Charles River daffodils are a neutral and beautiful addition to the parks

Definitions sourced from: USDA 


TOPIC TWO: How do Native and Invasive Plants Impact their Ecosystem?

This topic is focusing on the ways native and invasive plant species affect their ecosystems! Once you’ve read through the information below, test your knowledge with the game!


Native plants staghorn sumac and Sweet Joe-Pye-weed among others in the Charles River parks.

Native plants are beneficial to their ecosystem because they are naturally suited to the local climate and soil conditions and thus require less fertilizers and pesticides than non-native plants. Once established, they are low maintenance and can flourish with less watering and pruning than many non-native varieties.

Native plants are also much better at supporting other plant and animal species in their ecosystem than non-native plants. For example, entomologist Doug Tallamy showed that native oak trees are home to over 500 species of caterpillars. In contrast, ginkgos, a common non-native landscape tree from Asia, can host only 5 species of caterpillars. Since the presence of small bugs like caterpillars can have a drastic effect on the rest of the food chain, especially the chickadee bird in the case of the oak tree, planting native trees and shrubs is a great way to support the whole ecosystem.

Sources: US Forest Service & National Audubon Society


Two invasive species, Japanese knotweed and Phragmites, spread through a wetland habitat.

Invasive plants pose a threat to the ecosystem around them because they can often grow quickly and spread widely through an area without interference, which can hurt other plant life. Native plant populations are normally controlled by certain factors like diseases, parasites, and predators, which keep populations of each type of plant in check. However, invasive plants are often unaffected by these factors because they are not native to that ecosystem. For example, many types of invasive plants are toxic or extremely distasteful to local wildlife. Since these invasive plants aren’t being eaten as much as native plants are, they can grow faster than other plant life and spread further.

When invasive species grow excessively, they damage or kill other plants in their ecosystem because invasive plants are often able to out-compete other plants for important resources like water, nutrients, and sunlight. In fact, the US Forest Service reports that invasive species have contributed to the decline of 42% of US plant species that are considered endangered or threatened. When invasive species outcompete native plants, biodiversity is reduced within the ecosystem as many different types of native plants die off and only a few species remain. Without the natural variability of life in an area, the ecosystem can become more vulnerable to things like disease and natural disasters

Source: US Forest Service


TOPIC THREE: What are some Native Plants in the Charles River Parks?

Take a deeper dive into the native plants that call the Charles River parks home. Learn how to spot them, where you might find them, and how they support their local ecosystem.  Then test your knowledge with our 5 fun guessing games!


“Blooming Common Milkweed” by USFWS Midwest Region. Public Domain Mark 1.0. Link.

Common milkweed is a beautiful, native plant that grows to about five feet and produces large balls of fragrant, pink and purple flowers. Although you’ll find different varieties of milkweed across the US, the common milkweed is a variety native to the Northeast. You can spot this gorgeous plant blooming and attracting butterflies and bees along the Cambridge shoreline in the summer. The milkweed plant also plays an important role in the life of the monarch butterfly. Through years of coevolution, the milkweed plant has become the only place that monarchs butterflies can lay their eggs and the only food that monarch caterpillars can eat. In addition to supporting the monarch butterfly population, the milkweed plant also provides nectar for many other butterflies, bees, and beneficial insects. 

Source: USDA


“Winterberry” by liz west. Licensed under CC BY 2.0. Link.

Winterberry is a native shrub in the holly genus that gets its name for its beautiful, bright red berries that persist into winter and provide a spot of color through the colder months. You may also spot this plant with small, inconspicuous white flowers in the spring, full green leaves and red berries in the summer, and a beautiful mosaic of yellow and red leaves in the fall. The fruit of the winterberry is eaten by small mammals and more than 48 species of birds, especially through the winter when other sources of food have become scarce. The bush of the winterberry provides cover and nesting grounds for many animals as well. If you’re strolling around Magazine Beach in the winter, keep an eye out for this beautiful red plant and the robins, bluebirds, and mockingbirds that may be enjoying its fruit. 

Source: USDA


“20100713 Bidwell SilverMaple Cutler 8927” by Wendy Cutler. Licensed under CC BY 2.0. Link.

The silver maple is a sturdy, drought-resistant, and pollution-tolerant tree that is a beautiful and resilient addition to any urban park. Silver maples can be distinguished from other maple trees by the silver underside of their leaves, which create a stunning visual on windy days. Not only do silver maples provide shade for park goers and homes for birds and small animals, they also serve an important ecological purpose. The roots of the silver maple help to draw water from the lower soil layers and emit the water into the upper soil layers, which helps the tree and many other plants growing near it. Small animals eat the seeds of the maple, larger animals eat the leaves and stems, and many types of birds roost in the branches. Next time you are out in the parks, keep an eye out for red-winged blackbirds, starlings or brown-headed cowbirds that are often found among the tree branches.

Source: Lake Forest College


“683. Staghorn Sumac” by InAweOfGodsCreaton. Licensed under CC BY 2.0. Link.

The staghorn sumac is a beautiful and sturdy native plant that gets its name from its thick, hairy branches that resemble the velvety antlers of a male deer. Although this plant has a poisonous cousin, the poison sumac, the staghorn sumac is easily recognizable by its upright cones of red, fuzzy berries. If you happen to be near Magazine Beach in the fall, watch as the sumac leaves change from green to orange and then keep an eye out for the plant’s dazzling red berries which stick around long into the winter. In the colder months, you may see birds like northern cardinals or ruffed grouse eating the sumac berries or small mammals like rabbits and deer grazing on the leaves and stems. The fuzzy berries of the sumac plant also provide nectar for beneficial insects.

Source: Canadian Wildlife Federation


“New England Aster” by USFWS Midwest Region. Public Domain Mark 1.0. Link.

The New England aster is an easily recognizable and beloved late-season wildflower. The pink and purple flowers of this bushy plant can be found towards the end of the summer along the Cambridge shoreline. The aster flowers are known to be great for pollinators and a common spot for pearl crescent and silvery checkerspot butterflies to lay their eggs. Stopping by these beautiful flowers in the summer, you may notice butterflies and bees buzzing around and other small mammals using the plant for shelter. The New England aster is a great choice to plant in a home garden because it is easy to care for once established, will attract butterflies, and will bring a burst of color through late summer into the fall. 

Source: Wild Seed Project


Navigate between each of the 5 games using the arrows at the top of the game page.

TOPIC FOUR: How do Invasive Plants Impact their Ecosystem?

Just as there are many beautiful, native plants that support the ecosystems of the Charles River parks, there are also some invasive species that have become dominant in certain areas. It is important to learn about these plants so we can work to control their spread and understand their impact on local habitats. Once you’ve read about some of the the invasive species found in the Northeast, test your knowledge with our 5 fun guessing games!


“Phragmites (are you impressed?)” by Randy Robertson. Licensed by CC BY 2.0. Link.

While Phragmites, or the common reed, has at least one strain that is native to the US, the non-native phragmites was accidentally introduced to the US from Europe in the late 18th century through a ship’s ballast. Now, the non-native Phragmites is the most common strain in the Northeast. Phragmites reeds grow rapidly (up to 15 feet tall) in dense thickets in wetland areas. Belowground, the roots of the reed can spread 10 feet or more in one growing season, making them very difficult to dislodge. The non-native Phragmites can alter the hydrology and salinity of the wetland where it lives, which makes it harder for other plants to survive in that same area. When the Phragmites takes over an ecosystem in this way, natural biodiversity is lost, threatening the animals that depend on the diverse wetland ecosystem for food and shelter.

Source: New York Invasive Species Information


 “Black swallow-wort seedpods” Photo courtesy of the Minnesota Department of Agriculture. Link.

Black swallow-wort is an invasive climbing vine that is native to the Mediterranean. Black swallow-wort grows long vines that produce small star-like flowers in early summer and long seed pods in late July, which break open and dispense seeds through the wind. A square meter of swallow-wort can produce 1,000-2,000 seeds per year. Black swallow-wort can also be harmful to local animal species. Deer and many types of insects find swallow-wort to be either toxic or very distasteful, and avoid feeding on it. Monarch butterflies often mistake swallow-wort for common milkweed, since they are part of the same family of plants, and lay their eggs on the swallow-wort vines. Since the larvae of the monarch will die if they eat the swallow-wort, any eggs laid on the invasive vines are essentially lost, hurting local monarch butterfly populations.

Sources: New York Invasive Species Information and Monarch Joint Venture


“Garlic Mustard Flowers” by Wendell Smith. Licensed under CC BY 2.0. Link.

Garlic mustard is an invasive herb that was introduced to the US on Long Island 150 years ago and has spread through much of the eastern US and some areas on the West Coast. Garlic mustard spreads through disturbed areas in forests and can quickly establish itself as the dominant undergrowth in many wooded areas. Garlic mustard takes two years to fully develop into a mature plant, but once that happens, the plant can be identified by the light green, triangle-shaped leaves, the small white flowers that bloom in late spring, and the faint odor of garlic that the leaves make when they are crushed. As with many invasive plants, garlic mustard spreads by out-competing other plants for resources like sunlight and nutrients. However, garlic mustard is unique in that it is also allelopathic, meaning it can release a chemical that will hinder the growth of other plant species near it, limiting natural biodiversity. 

Source: New York Invasive Species Information


“DSC02677” by Jay Cross. Licensed by CC BY 2.0. Link.

Oriental bittersweet is an invasive woody vine that was introduced to North America in the 1800’s as an ornamental plant. While there is a less common and often innocuous native bittersweet, the invasive species grows vigorously in many different wooded areas and conditions. Bittersweet can be identified by its characteristic red berries that grow out of yellow leaves in the fall. Bittersweet can form thick masses of vines that sprawl over shrubs and trees, collapsing them into shade and weakening them from excessive weight. The vines may also strip the tree of its bark while twining around the trunk, a process that arborists call ‘girdling’, which damages the tree. The bittersweet vine is very difficult to remove once it is entangled with the trees and shrubs below it. 

Source: Center for Invasive Species and Ecosystem Health


“Japanischer Staudenknöterich (Fallopia japonica)” by Maja Dumat. Licensed by CC BY 2.0. Link.

The Japanese knotweed plant was introduced from Eastern Asia to the US in the 1800’s as an ornamental plant. While knotweed can be very beautiful with large bamboo-like stems that can grow to up to 15 feet and sprays of small white flowers that bloom in late summer, it can also be very destructive. Japanese knotweed spreads rapidly through disturbed areas along streams and in low-lying spots and forms dense thickets. It is very difficult for other plant life to survive in the shade of the broad knotweed leaves so the ground underneath the plant tends to be very bare. Because of this, the ground is often susceptible to soil erosion, especially in areas along streams or rivers. Once established in a certain area, knotweed is very difficult to fully remove. 

Source: New York Invasive Species Information


Navigate between each of the 5 games using the arrows at the top of the game page.

TOPIC FIVE: How Can I Support Healthy Ecosystems in My Own Community?

Being able to identify and understand the difference between beneficial and harmful plants helps us be better advocates for our local ecosystems. Check out the sections below to see how you can get involved in the ecology of your own backyard and test what you’ve learned from all five topics!


A monarch caterpillar munches milkweed! Get creative and make this image your own with our coloring pages!

Test everything you’ve learned! Do you remember which plants are native, which are invasive and how they impact their surroundings? Challenge yourself with this quiz

Snap a picture of the natives you encounter in your backyard or local park. We want to spread the joy of spring and highlight these great native plants in action. Learn more about how to submit pictures and be entered to win a prize!

Share what you’ve learned with your neighbors by logging any plants you encounter with iNaturalist, a database of millions of wildlife observations submitted by people all over the world. You can also identify any unfamiliar plant you spot with the corresponding app, Seek

Support native plants in your own backyard by browsing these resources:


Invasive bittersweet removal.

Now that you’re equipped to spot common invasive plants in your backyard and beyond, remember to only tackle the invasive plants on your own property – any invasives in the parks are a job for the state or local government.

Learn about how invasive species are managed in the parks: In order to control the spread of invasive species in the parks, the MA Department of Conservation and Recreation (DCR) is currently updating their vegetation management plan for the Charles River Basin. This plan will address best management practices and techniques for managing riverbank vegetation, including invasive plants. The CRC is partnering with the DCR to pilot an invasive plant control project in Hell’s Half Acre. Read more about this exciting project.  

Tackle the invasive species in your own backyard

  • Start by checking with your local government for any regulations and information pertaining to invasive species removal in your area.
  • Be prepared for a long haul – these plants have biological designs that make them hard to get rid of, so don’t give up!
  • Plan to remove the plants early in the season, before they flower, so there is less chance of any seeds spreading during removal
  • Don’t leave the plant material lying around; follow disposal guidelines for the specific plant so there is less chance of re-introduction
  • Plan to replace the invasive plant with a native species known to emerge early and compete strongly for resources. 

Some invasive plants are easier to remove than others and some require special techniques. Check out these resources for specific information on Oriental bittersweet, garlic mustard, black swallow-wort, and Japanese knotweed.


Lead photo by Aaron John Bourque