A mature plant has hollow robust stems with distinct raised nodes similar to those of bamboo. These can grow up to 13 ft (4 m) each season.
The flowers of creeping thistle are of a pink-purple color, all have a similar form, and are composed of many thin petals.
When are only saplings, the paulownia tree can be easily mistaken with a gigantic weed if you’ve never seen one before. It has a thick and tall stalk and large flat green leaves.
6. Wild Lettuce
Common Mullein by Ryan Hodnett / CC BY-SA
Hopefully, this post will help someone identify a mysterious plant growing in his or her yard one day.
8. Creeping Thistle
Despite its pleasant appearance, Ricinus is one of the most poisonous plants in the world. All its parts, especially the beans-like-seeds, contain a deadly naturally occurring toxin called “ricin.” Ricin can be lethal for both humans and animals.
Giant hogweed has a stiff stalk that can grow more than 4 m (13 ft) high and up to 10 cm (3.9 in) in diameter. A mature plant has gigantic incised and intensely lobed leaves that can reach between 1 and 1.5 m (3-4 ft) wide.
Triclopyr is available in either amine or ester formulations, with triclopyr ester being more effective on pokeweed. Products containing a minimum of 61% active ingredient of the ester formulation can provide good to excellent control when applied at 1 to 1.25 ounces of product per gallon of water (0.75% to 1.5% of the total solution). One such product with this concentration is Brushtox Brush Killer with Triclopyr. Other ester formulations with less concentrate are also available including Crossbow. Mixing triclopyr ester with commercially available seed oils can offer better penetration. One available product is Southern Ag Methylated Seed Oil. Mix this at 1.25 ounces of product per gallon of herbicide solution (1% of the total solution). Triclopyr is also available in the amine formulation. Products available include Bayer Bio Advanced Brush Killer Plus, Ortho Brush-B-Gon Poison Ivy and Poison Oak & Brush Killer, and Monterey Brush & Vine Control.
While Pokeweed has been used in folk medicine to treat numerous health problems and is still used in many herbal remedies today, medical research has not shown whether pokeweed is indeed effective in treating many of these ailments. Recently a protein in the plant “pokeweed antiviral protein” shows promise in being used in treating cancer, herpes, human immunodeficiency virus (HIV), and for conferring broad spectrum disease resistance in agricultural crops.
Pokeweed’s above-ground growth dies back after the first Fall frost, leaving large skeletons that breakdown over the winter. In the Spring, plants resprout from a large fleshy taproot.
Pokeweed flowers in mid-summer. Flowers are borne in white-pinkish clusters that hang from the branches. Flowers consist of 5 white sepals, no petals, and are erect when in bloom and begin to droop as fruits develop. Flowers are self-fertile resulting in high fruit set. Immature berries are dull green, turning glossy purple-black at maturity in late Summer.
The drizzle application method is good in situations of dense planting, or when it is difficult to cover an entire area due to topography. Glyphosate formulated into a product with 41% active ingredient can provide good to excellent control of pokeweed when applied at 13 ounces of product per gallon of water (10% of the total solution).
Concentration. For spray-to-wet applications, products containing at least 41% glyphosate as the active ingredient can provide good to excellent control of pokeweed when applied at 3.75 ounces of product per gallon of water (3% of the total solution). Some products available for use in the home landscape with this concentration of active ingredient are Roundup Pro Concentrate®, FarmWorks Grass & Weed Killer 41% Glyphosate Concentrate, RM43 Total Vegetation Control, Compare-N-Save Grass & Weed Killer Concentrate, and Remuda® Full Strength. Glyphosate products that have a lower concentration of active ingredient, such as Roundup Weed & Grass Concentrate (18% active ingredient), will require about 6 ounces of product per gallon of water (4.7% of the total solution) for effective control.
When you're unsure, you can text an image of the suspect to a friend and ask for their opinion (which my friends often do), or, you can use these tips from Jon Peter, the curator and manager of plant records at the Royal Botanical Gardens in Hamilton, Ontario. Then you can make the call to yank it or leave it all by yourself.
A plant expert answers questions about every gardener’s nemesis
JP: There are a number of weeds which are considered noxious or invasive and they are generally defined as species whose introduction or spread threatens the environment, the economy, or human health. In Ontario alone, there are over 400 species considered to be invasive. In Canada, invasive plants cost an estimated $2.2 billion each year by reducing crop yields and quality and increasing the cost of weed control and harvesting.
But no matter how many weeds they've plucked, even veteren gardeners get stumped at times trying to determine what is, and what is not, a weed — particularly in the spring when everything is just beginning to peek out of the soil and your winter brain has wiped all your geographical gardening memories clean. "Is this where I planted a patch of Primrose or are these weeds that need to be annihilated?"