Invasive Garden Plants: Is That a Weed?
Original article by David Graper, former SDSU Extension Horticulture Specialist and Master Gardener Program Coordinator. Updated by Kristine Lang, Assistant Professor and SDSU Extension Consumer Horticulture Specialist.
If there is one thing that can be said about a garden, it is that there are almost always weeds to pull. One of the classic definitions of a weed is “a plant that is growing out of place.” While we most generally consider common plants, such as crabgrass, dandelions, purslane and many others, as weeds, just about any plant in the wrong location can be considered a weed at times. Whether or not you personally would consider a particular plant a weed could also depend on how much of that plant you have already and how much of the garden that plant has already taken over.
Gardeners and garden writers have various names for some of these more “aggressive” plants, such as “spreading,” “invasive” or “thug,” plus a few more-colorful terms, which some gardeners might use under more private circumstances. Then, just about the time you are about to eradicate a particular plant from your garden forever, a friend stops by, and that is just the plant they are looking to plant in a particularly difficult site. It is as if the old saying “one man’s trash is another man’s treasure” becomes “one gardener’s weed is another gardener’s pleasure.” So, here are descriptions of some of the most-common garden perennial plants that you may want to consider carefully before planting based on your garden size and on your tolerance for spreading plants.
Shasta daisies (Leucanthemum x superbum) are generally a welcome sight in the spring garden, with blooms showing up in June and extending through September with proper deadheading (Figure 1).
Their showy, white flowers with the yellow centers are pretty and make great cut flowers. However, unless you have some of the more well-behaved cultivars, the typical species, Leucanthemum x supurbum, is an aggressive spreading plant. What starts as a nice clump of a few plants can soon be a mass of hundreds taking over a large section of your garden.
Shasta daisies spread mainly by seed, so if you cut off the flower stalks when the flowers fade, you will reduce the chances of it spreading. But if you want to grow Shasta daisies without fear of a garden takeover, look for some of the named varieties, which tend to either produce little viable seed or do not spread from the base like the species might.
Yellow Archangel (Lamium galeobdolon) is a rapid-growing groundcover vine for shady places, including under trees (Figure 2).
It has attractive, silvery foliage all summer long, but particularly in the spring. In early summer, small, yellow flowers develop at the base of each leaf, giving a nice display of color. While this plant can fill in heavily shaded sites where little else will grow, the aggressive qualities have their downside. Like the Aegopodium that is described below, this plant can take over if you are not careful. In somewhat warmer climates, it has pushed out native species and covered large areas of the forest floor, where it can be difficult to control.
Like the Leucanthemum, there is at least one cultivar called ‘Herman’s Pride’ that is not aggressive at all. Instead, it forms nice clumps of upright stems with the same yellow flowers. Its leaves are about one-quarter the size of the species form, but it is much better behaved.
Pale Indian Plantain
Pale Indian Plantain (Cacalia atriplicifolia) is a native, tall-grass prairie plant that is sometimes planted in our area (Figure 3).
It grows to form a basal rosette of leaves that may spread to a foot wide. In late-spring, a flower stalk grows up that can reach five feet or more, producing a branched panicle of pale, greenish white flowers.
After the flowers mature, they produce little seeds with a white tuft attached that makes them easy to be carried by the wind. New plants are easily produced around the garden. While this is an interesting plant, it may not be interesting enough to warrant the need for deadheading and then digging out the unwanted baby plants.
Garden Valerian (Valeriana officinalis) flowers in the late-spring to early-summer months and is most commonly known for the potential medical properties of the root (Figure 4).
Garden Valerian grows about two-to-three feet tall and has a white flower head. Some people think the flowers have a pretty, vanilla fragrance, but in large quantities, some say the flowers smell like feet – and not in a good way.
They spread readily by seed and by rhizomes (horizontal underground stems) – soon you can have them popping up in fairly large areas, particularly in moist areas of your garden, as they prefer occasionally wet soil. Pulling out rogue Garden Valerian by the base of the plant and deadheading are both options to keep this plant in check.
Cup Plant (Silphium perfoliatum) is native to South Dakota and a good floral resource for pollinators (Figure 5).
Silphium is a member of the Aster family, so it has daisy-like flowers that develop seed that can be wind-blown from the original plant. This is no small plant. A mature plant can reach six-to-eight feet in height with a three-foot spread, so when it decides to settle down amongst much smaller plants, it is very noticeable. Mature plants have fairly large, one-half-inch wide stems that are square. The cup plant name comes from the way the bases of the leaves clasp the stem and can hold water after a rain.
The seedling plants can be a little difficult to identify. Look for the roughly-textured, opposite leaves on a fairly large plant for a seedling. You may not notice the square stem or cupped leaves until they get a little larger. You may need a shovel to dig these guys out, because they develop a pretty good root system at an early age.
Pale Pincushion Flower
Cream Scabious, or Cream Pincusion, (Scabiosa ochroleuca) is a biennial plant that can catch you by surprise a few years after being planted in the garden (Figure 6).
It spends its first year as a small, unassuming clump of somewhat fuzzy leaves growing close to the ground. It does not flower the first year, but rather stores up carbohydrates for the winter and next year’s floral display. By mid-summer of the next year, the plant has grown up to three feet in height and may reach three feet in width by the end of the summer.
It produces dozens of one-inch-wide creamy yellow flowers that are produced on fine, wiry stems. The anthers stick up on tiny, little pin-like stalks, giving the plant its common name. All of those cute little flowers produce lots of seeds, which, when ripe, also look like more pins stuck in a pin cushion. It soon falls free to spread around and plant next year’s crop of seedlings. The first-year plants are easy to pull out, but are often missed, because they are not that showy in the garden.
Snow-on-the-mountain (Aegopodium podograria) is a favorite plant of both authors, but only for the right kind of locations where the plant can spread without creating headaches for all involved. This plant spreads mostly by underground stems called rhizomes, soon making a dense groundcover that outcompetes weeds as well as other garden plants (Figure 7).
It grows well in shade; although, when grown in full shade, it may not flower. Snow-on-the-mountain may get scorched leaves during the heat of the summer or when grown in full-sun conditions. The variegated form is the one that is most-often planted. It has a three-part dissected leaf with white margins along the edges. In early summer, it produces a white umbel flower, like that of dill, but smaller. The plant only grows about eight to 10 inches-tall, except when it is blooming.
This is a great plant to use under shade trees, where it can just grow as far as it wants. If you want to keep this plant in check, you may need to use landscape edging, pavers and occasional hand removal of plants that step out of line.
References and Resources
- Armitage, A. 2020. Herbaceous Perennial Plants: A Treatise on their Identification, Culture, and Garden Attributes. (4th Ed.) Stipes Publishing. Champaign, IL, USA.
- North Carolina State Extension. North Carolina Extension Gardener Plant Toolbox.
Special thanks to SDSU Extension Master Gardeners Tim Schreiner and Stacy Dreis for serving as volunteer copy editors of this article.
11 Plants That Look Like Weed But Are Entirely Legal (With Pictures)
Experienced gardeners know about the plants they are growing. They understand how the plant looks like when growing or fully grown.
But sometimes beginner gardeners often get confused with the plants that look like weed but isn’t a weed.
This happens so often that you may imagine that law enforcement may not get confused about plants’ similarity with other weed-like plants.
Let’s look at 11 plants that often get mistaken to be weeds.
What do marijuana leaves look like?
Knowing what does marijuana leaf look like is the best way to identify whether a plant is a weed or not. A marijuana leaf is the leaf of a cannabis plant. It usually consists of large, broad leaflets with opposite/alternate leaves or both on the same plant. Each leaf has a series of smaller, serrated, and pointed leaflets.
The top of the leaf has dark green color than the underside. The shape of the leaflet is often likened to a maple leaf but much shorter. The weed leaf is made of 1 to 16 coarsely toothed palmate leaflets.
It grows from a common stalk and can reach up to 8 inches long. It has short hairs at the top of the leaf, and the bottom of the leaf has long simple hairs.
1. Japanese Maple
Japanese maples are plants that look like a weed. You can grow it in a container or outside in the garden. It comes in several different varieties with different styles of leaf shape and color.
When the plant is still at a growing stage and has green leaves, it looks like Cannabis. This cannabis look-alike plant grows in Japan, Korea, and central China.
2. Coral Plant
The Coral plant is also known as Jathroha Multifida and has leaves that look very similar to weeds. Many people get confused with the texture and style of its leaves, which have sharp cuts and more extended sizes.
This is a tropical plant and is grown primarily for its leaves and red flower bunch. This plant looks so similar to wild weed that some dealers try to sell it as a real weed to unknown marijuana users.
It’s mainly found in Mexico and Central America as the weather is more tropical at those places.
Okra is another plant that looks like a weed, especially its buds look very similar to weed buds. In fact, this has such a similarity with the illegal pot that cops in Cartersville mistook it to be weed and arrested a man who had grown Okra in his garden.
In reality, the Okra is an edible plant that is usually grown in warm and tropical climates such as in South Africa and Asia. Many southeast Indian cuisines use Okra in several of their dishes.
If you mistook Okra to be Cannabis and eat it, then don’t worry, as it has lots of nutrients which is right for your body.
4. Cranberry Hibiscus
Cranberry Hibiscus has the Latin name of Hibiscus Acetosella and is also known as African Rosemallow. It has large colorful leaves that look like cannabis leaves.
Once fully grown, the leaves turn out to be broader and look like a Maple leaf, but it can be easily mistaken for cannabis leaves when the plant is still growing.
Due to its high similarity with the marijuana plants, people like to plant it in either containers or indoors when it’s small. After it has started blooming, the flower and leaves look quite different than weeds plants.
You can use the flowers and leaves of the Cranberry Hibiscus with salads or other dishes or use them as a natural food color.
The plant looks like a weed, but it has no THC, you won’t get high after consuming it.
Cassava is mainly known for the medicinal properties of the roots. The roots are quite poisonous if you eat raw. To eat it, you have to cook it properly, which removes the harmful hydrocyanic acid from the root.
The leaves of Cassava look like marijuana as it has light greenish color leaves like Cannabis. The leaves are directly attached to the stem and are grown in the bunch.
However, its similarity to the weed ends there. It’s grown for starch and used for human and industrial consumption.
Sweetfern is a primarily invasive weed, which grows in the yards and gardens. It’s part of the bayberry family and native to eastern Canada and the U.S.
Its fern-like leaves give the appearance of marijuana leaves, but it’s quite aromatic when rubbed. These smells feel similar to smokable pots that make people get confused as they think that it’s some different variety of Cannabis.
The leaves grow in multiple bunches from a single stem. As the plant grows further, the leaves spread out. It’s entirely legal to grow sweet fern wherever you want.
Although the plant looks like a weed, in reality, it’s just another herbal plant.
Cleome may not look like a wild weed plant when it’s flowered with bright red and purple color flowers. But while growing up, it gives the appearance of weeds. The leaves are long and spikey similar to a pot.
The Cleome flower is also known as the spider flower due to its long tentacles stretching from the flower stem. It typically blooms in summer and lasts till the frost starts.
You can plant Cleome as an edible plant. It also attracts beneficial insects in the garden.
8. Texas Star Hibiscus
Texas Star Hibiscus is a slender, multi-branched plant that has leaves grown like Cannabis. The bright green color leaves don’t have very sharp pointy edges, but their long thin textured leaves create the illusion of a cannabis plant.
For people familiar with the pot or who have experience growing it, they won’t consider the Texas Star Hibiscus plant to look like weed. Still, casual users, they may indeed get confused.
When fully grown, it blooms crimson red or white color floor, but at the growing stage, it resembles more to the pot plant.
As the name suggests, the natural growing area of this plant is in Texas with flower blooming time from June to October. This is a very versatile plant and can be grown in moist and well-drained soil. It needs full sunlight to flourish and is perennial in nature.
Kenaf is known as Hibiscus Cannabinus in the scientific community. It’s grown primarily for food and fiber. But these plants resemble so much like a weed that your home visitors may think that you are into some bad company.
Like other commonly mistaken plants that look like weed, Kenaf has considerable similarity to Cannabis plants. A similar characteristic comes from the texture and leaf size of the plant.
It has star-shaped leaves with serrated edges. A stem may have a collective bunch of 7 blades that look similar to marijuana plant leaves.
In fact, this plant looks so similar to Cannabis that its scientific name has Cannabis terminology in it.
Just be careful when growing Kenaf in your home as you don’t want your concerned neighbor to call the police and report you to have illegal grow up.
10. Tagetes Minuta
Tagetes Minuta is also commonly known as Muster-John-Henry. It grows up to 1.2 m in length and 0.6 m in width, similar to cannabis plants.
The leaves are long, elongated, and finely serrated resemble the pot leaves. When the leaves are rubbed, it smells like licorice.
With fully-grown stems, the plant blooms white and yellowish flowers, which gives the telltale sign that it’s not a weed plant. But when it’s small and growing, the plant looks like very much a weed plant.
The Tagetes Minuta is native to South America, but it’s also commonly grown in other parts of the world. The plant has several medicinal properties as it is found to be invasive and effective in controlling fungi, bacteria, and roundworms.
11. Chaste Tree
The Chaste Tree, when fully grown, does not look like a wild weed. But when it’s still small and growing up, the plant looks very similar to a pot. The leaves are long and serrated like Cannabis, and each stem contains 5 to 6 leaves like hemp or other cannabis leaves.
When fully grown, it doesn’t look like a shrub anymore and becomes easy to know that this is not a weed plant. But at the initial stage, the plant has a very high resemblance to the weed.
Overall, the plant grows 8 to 12 feet tall and wide. The leaves are quite aromatic, and the plant bears the violet color flowers. The flower grows like lavender, which, when bloomed, attracts bees, butterflies, and other beneficial insects in the garden.
You should regularly prune the chaste tree plants as if left unchecked they can grow up to 15 to 20 feet tall. The pruning shears helps with shaping and adequately sizing the plant.
About Plants That Look Like Weed: Final Thought
Although marijuana plants are becoming legal in most parts of the world, such as in Canada and some parts of the U.S, it’s still widely considered to be illegal in most places.
The cannabis plants have a distinct look, and the hallmark of their appearance is the leaf. The long serrated and pointed leaves give the telltale sign that it’s a marijuana plant.
Many companies also use pot leaves distinct look like a representation of hemp. This creates confusion for people who are not actually familiar with the marijuana plant. They often mistakenly assume plants with similar leave to be pot plants.
In some cases, it may cause inconvenience to the planter as the law enforcement gets involved in investigating if you are doing illegal grow up.
Knowing the plants that look like weed gives you some caution before planting or explaining it to your suspicious neighbor before they dial law enforcement to report about you wrongly.
Do you want to know the Perlite Vs Vermiculite Difference? Read that post here.