This page is dedicated to the volunteer plants in the garden. Some will be ones you definitely want to pull and throw out and others could be left to grow—more the gardener’s decision on whether it is a useful plant or a weed.

Black henbane (Hyoscyamus niger)

This is a pull and throw plant. It is on the invasive species list as a noxious plant and musts be controlled. Wear gloves when pulling to avoid contact as it may cause a rash. Place all plant material in the black bin for disposal. To learn more about this plant read the fact sheet on the Alberta Invasive Species Council website (

Photo by Mae Campbell.

Black Medick (Medicago lupulina)

Black medick is an annual in the legume/bean Leguminosae) family. Native to Europe and Asia, it can now be found across Canada and is also known by its other names, yellow trefoil, hop clover, or black clover.

Black medick belongs to the same genus as alfalfa and can be mistaken for clover when it is young. Its leaves are compound (made up of two or more discrete oval leaflets), similar to a clover leaf. The plant has a tap root and is low growing with wiry stems that extend flat along the ground reaching up to 76 cm wide. Its individual yellow flowers are grouped in a dense spherical flower head about 1 cm in size. Black medick reproduces only by seed through black pods (hence its name) which drop kidney-shaped seeds from early spring to late autumn. Given the right conditions, a lone plant can produce around 6,000 seeds, which can remain viable for several years. Common in lawns, gardens, pastures, and cultivated fields, it can quickly become invasive. Read more about this plant by visiting the Ontario Ministry of Agriculture, Food and Rural Affairs, Ontario Weeds: Black medick webpage.

Photo by Jessi-Ann Riddell.

Chickweed (Stellaria media)

Chickweed is a cool weather plant that is both a native and introduced species in Canada. It has stringy, but succulent stems that can grow up to a foot and a half. During its growing season it produces tiny white flowers. The flowers often resemble carnation flowers, hence why Chickweed is part of the carnation family, Caryophyllaceae. Chickweed is found in lawns and sunny areas, as well as areas with moist soil. It is often found during the fall. Some distinguishing features of Chickweed are that it does not have milky sap, its inner stem is somewhat elastic, and that it has a line that runs along its stem. It is recommended that chickweed is grown as it contains beneficial elements such as phosphorus and potassium which supports beneficial insects and pollinators. Chickweed is also an edible plant and poses nutritional benefits to humans as well. It serves as a great salad base, or a good addition to sandwiches.

Photo by Deborah Maier.

Clover, Alsike (Trifolium hybridum)

Originating in Europe, alsike clover is a semi-erect perennial of the Fabaceae family with inflorescences of flowers with white petals that turn pink as they age. This gives the flower a distinct two toned appearance (white top and pink bottom) which helps to distinguish this plant from red and white clover. The compound leaves contain three, solid green, ovate leaflets that lack the lighter pattern notable on red and white clover leaves. Alsike clover prefers cool, moist
conditions and full sun. It is well adapted to heavy, poorly drained soil and can tolerate occasional flooding. It is often found growing on the side of roads and in ditches. The leaves and flowers of alsike clover are edible for humans but are toxic to horses and other equines.

Gloves should be worn when handling the plant as it can irritate the skin. Cultivation purposes are much the same as red clover, however alsike clover is commonly planted as a mix with other seeds (grass, red clover). It is an important pollinator plant for bees and an excellent source of nutrients for the soil.

Photo by No-longer-here from Pixabay.

Clover, Red (Trifolium pratense)

Red clover is a biennial or short-lived perennial with a semi-erect habit native to Europe, Western Asia, and NW Africa. It is cultivated as a forage crop and for medicinal uses and is a beneficial pollinator plant for bumble bees. While you may not want it growing in your manicured lawn, you might want to keep it in naturalized areas or even grow it instead of grass. It is drought tolerant and will grow in sun or shade and in places where grass will not. It is self-seeded and can spread by rhizomes. A member of the legume (Fabaceae) family, it is a nitrogen fixer and is beneficial to soil health. Red clover can be identified by its compound leaves composed of three oval to oblong leaflets with a lighter green ‘v’ pattern in the center. In late spring to early summer the pink to purplish/pink, round, terminal inflorescences help to distinguish red clover from other clover species.

Photo by Couleur from Pixabay.

Clover, White (Trifolium repens)

White clover is a creeping perennial growing four inches tall with a 30 cm spread. It will spread aggressively on creeping stems which form roots at the nodes. Unless it is being used as a ground cover or lawn replacement it should be kept in check. Flowers bloom in late spring. The round inflorescence is composed of 20-100 white flowers that fade to light pink with age. The three leaflets have a white crescent marking on their upper side. White clover is native to Europe, North Africa, and Asia but is now naturalized throughout the world. Like red clover it is cultivated as a forage crop for animals, as cover crop, or green manure. In the garden, because it will grow where grass will not, white clover is often used as a companion plant or substitute for grass. It prefers moist soils in light shade but is resilient and will grow in full sun and dryer soils. It provides important nutrients to the soil and is a food source for pollinators, livestock and humans.

Photo by Emilian Robert Vicol from Pixabay.

Creeping bellflower (Campanula rapunculoides)

Creeping bellflower is a perennial that flowers early in the summer. It has heart-shaped leaves and purple bell like flowers, that begin to bloom on the lower stem of the plant. Creeping bellflower often grows up to 1 metre tall. It is a highly invasive and aggressive plant that invades lawns and gardens. Therefore, it is recommended that this plant is thrown and dug out immediately. Ensure that you dispose of the plant in the black cart and not the compost. For more information, click on the following link, City of Calgary: Creeping Bellflower. 

Photo by Deborah Maier.

Dame’s rocket (Hesperis matronalis)

Dame’s rocket is a perennial that is quick spreading and invasive. It is usually one metre tall and its stems are hairy and branched. It has flowers that have four petals and bloom in a variety of colors including pink, white, and purple. Dame’s rocket self-seeds, forming dense infestations quickly. It destroys natural vegetation and hosts dangerous plant diseases and pests. Take steps to reduce its spread. These steps include avoiding purchasing wildflower seed mixes that don’t list their contents, pulling out the plant when found, and placing any pulled plant material in a garbage bin for disposal. For more information, visit the link, City of Calgary: Dame’s Rocket.

Photo by Deborah Maier.

Dandelion (Taraxacum officinale)

Dandelions are a species of weed that are native to North America, Europe and Asia. It is a member of the family Asteraceae. It consists of a yellow flower head and a stem that contains milky sap. When the flower matures, it contains many single-seeded fruits called achenes, which create a sphere. Despite being a weed, dandelions have numerous health benefits and medicinal usages. They are rich in antioxidants and are used to reduce cholesterol, inflammation, blood pressure, risk of cancer and allow for the immune system to receive a boost. In addition to benefiting humans, dandelions also attract pollinators. That said, it is the gardener’s choice to grow this plant or throw it.  

Photo by Deborah Maier.

Foxtail barley (Hordeum Jubatum)

Native to North America, foxtail barley is a drought-tolerant perennial plant species in the grass (Poaceae) family.

Known for its resilience to high salinity, it grows in dense bunches from a mass of fibrous roots and reaches about 60 cm (2 ft) tall. Each 5–10 cm (2–4 in) long nodding flower spike sits atop a tubular hollow stem typical of grasses. On display from late spring until midsummer, the spikes are green, tinged with pale pink and purple, and then fade to light tan as they mature. The long silky tails are said to resemble the tails of red foxes. While they are considered a weed, the young flower spikes are soft and attractive as they wave gently in the breeze.

Foxtail barley reproduces only by seeds and is a prolific seed producer. The seeds can be carried a great distance by the wind and have sharp, backwards pointing barbs which can cause sores in the nose, mouth, and eyes of pets and livestock. Read more about this plant by visiting the Ontario Ministry of Agriculture, Food and Rural Affairs.

Photo by Jessi-Ann Riddell.

Note: The City of Calgary notes foxtail barley needs to be controlled on nuisance properties when over 8 cm in height. Learn more about bylaws related to grasses by visiting

Groundsel, common (Senecio vulgaris)

A member of the Asteraceae family, common groundsel is native to Europe. This annual is adaptable and grows in disturbed sites, waste sites, along roadways, in lawns, and gardens. The plant will grow up to 60.9 centimetres with a smooth, somewhat fleshy, erect stem developing from a shallow tap root. The leaves are alternate, deeply lobed, with fine to coarsely toothed margins. It has cylinder shaped, rayless, yellow flower heads with black tipped bracts around the base from June through late August. The common groundsel seed is tan coloured with white hairs and disperses primarily with wind. It reseeds prolifically throughout the summer and fall rosettes can over-winter. Common groundsel contains pyrrolizidine alkaloids and is poisonous to cattle and horses, and toxic to humans. It can also act as a host for fungus that causes black rot in several food crops and ornamental flowering plants. For more information, visit Inaturalist-Senecio Vulgaris for more information.

Photo by Deborah Maier.

Lamb’s quarters (Chenopodium album)

Lamb’s quarters is an annual plant from the Amaranthaceae family. It is native to many countries around the world. The weed has a distinctive white coating on its leaves and produces small, green flowers in clusters. The leaves are diamond shaped and grow up to 10 cm in length. The height of the plant averages around 1 m. Despite the plant being categorized as a weed, it is known to restore beneficial nutrients to nutrient-depleted soil. Furthermore, Lamb’s quarters is an edible plant and can be consumed in small quantities when cooked.  

Photo by Deborah Maier.

Rod-like flower spikes on plant with elliptical leaves

Plantain, common (Plantago major)

Common plantain is a non-native plant that thrives in compacted soils along footpaths and road margins. It tolerates mowing. It was brought to North America from Europe where it is native and has traditionally been used in folk remedies. Because it can tolerate trampling and soil compaction, it has an important role in breaking apart hard-packed soils, while holding the soil in place to prevent erosion.

This may be a case of right plant, right place. If you have the right place, maybe it can stay? Read more about this plant by visiting the Canadian Wildlife Federation site for edible wild and not so wild plants.

Photo by Deborah Maier.

Prostrate knotweed (Polygonum aviculare)

Prostrate knotweed is a low-growing perennial that is an invasive weed that releases toxins in the soil when it is not managed. You may identify this weed by its wiry stem and the ovular shape of its leaves. The size of the leaves ranges from 0.5 to 2 centimetres. The roots of the weed have been found to grow long and up to 76 centimetres. Additionally, they also possess light colored flowers. Compacted soil and poor aeration often lead to the growth of this weed. The weed also houses hazardous parasites, viruses, and fungi such as powdery mildew, therefore it is recommended that this weed is thrown away. Chemical control is the most effective method in controlling this weed and prevention can be done through regular fertilization of your lawn and reducing the amount it is walked on.  

Photo by Deborah Maier.

Purslane (Portulaca oleracea)

Purslane has been, and continues to be, cultivated for over 4000 years as a food crop and has been naturalized in most parts of the world. It is unusually high in omega-3 fatty acids and contains significant amounts of vitamins A and C making it more nutritious than your average weed. A member of the Portulacaceae family, it has smooth reddish coloured stems forming from a single taproot. The plant has a prostrate growing habit and will form a dense mat if left to grow. The
veinless green leaves are succulent, oval to spoon shaped, with a smooth reddish colored margin. It can have small yellow flowers with 4-5 notched petals that open on sunny days. Purslane is an annual that propagates through self seeding and stem cuttings. It grows in full sun tolerating almost any soil conditions, prefers warm weather, and is drought tolerant. It is best to remove the entire plant if you don’t want it in your yard as the seeds can remain viable in the soil for decades.

Photo by Deborah Maier.

Redroot pigweed (Amaranthus retroflexus)

Redroot pigweed is a plant native to North America that is often found in pastures and undeveloped areas. The stem of the plant is light green and stout and can grow 7-9 centimetres long, with leaves that are ovate and rough. The plant also has numerous small, green flowers. Redroot pigweed houses pests that can hinder the development of plants, therefore it is recommended that this plant is thrown. Small spaces can be easily managed by pulling plants.  

Photo by Deborah Maier

Shepherd’s Purse (Capsella bursa-pastoris)

Shepherd’s purse is easily distinguished from other members of the Brassicaceae family by its heart shaped seed pods that resemble a lady’s purse. A native of eastern Europe, all parts of this annual are edible, and it is sometimes grown for its medicinal properties and value as a food crop. A prolific re-seeder, it produces seeds throughout the growing season and fall rosettes can survive through the winter. The leaves on the basal rosette are lobed, oblong, usually hairy, with irregularly toothed margins. Smaller, slightly toothed, alternate leaves clasp the branching stems. The small, white flowers form on racemes at the stem tips in early spring through fall. It is a very adaptable plant and will grow in all soil types. It can be tasty in a salad, but will need to be kept in check as it can take over quickly. If you don’t wish to have it in your garden mature plants should be pulled before they produce seeds, spring and fall rosettes can be turned under.

Photo by Deborah Maier.

Showy Locoweed (Oxytropis splendens)

Showy locoweed is a drought-tolerant native plant. Around June, it will start to bloom. It has pretty purple/pink bonnet-shaped flowers common to members of the pea (Fabaceae) family.

It is available for purchase from nurseries specializing in native plants and is considered a good plant to use when xeriscaping or creating an alpine garden—could be a keeper!

For more information on this plant, visit the E-Flora BC: Electronic Atlas of the Flora of British Columbia (The interactive map shows North American specimen data collection sites)

Photo by Mae Campbell.

Sow thistle, annual spiny (Sonchus asper)

Easily confused with perennial sow thistle (Sonchus arvensis) or annual sow thistle (Sonchus oleraceus), spiny sow thistle can be identified by its leaves and roots. It has a tap root, like annual sow thistle, whereas perennial sow thistle has creeping roots. The leaves of spiny sow thistle are dark green with a purplish margin, look and feel very waxy, and are noticeably more spiny and pricklier than annual sow thistle. Spiny sow thistle is a member of the Asteraceae family and can grow up to two metres on a single erect stem that branches above and terminates in clusters of yellow ray flowers somewhat resembling dandelions. It propagates through seeds spread by the wind and will grow in almost any disturbed soil. Because it can reproduce quickly and is a host plant of several garden pests and viruses, it’s best to remove young plants before the tap root gets well established or the plant goes to seed.

Photo by Deborah Maier.

Stinging nettle (Urtica dioica)

Stinging nettle is a plant that has historically been used for medicinal purposes. It had leaves with fine hairs and white-yellow flowers. The plant has often been used to reduce inflammation and increase urination. It has also been used to relieve arthritis induced pain and allergies. That said, simply touching the leaves of the plant may irritate the skin. Therefore, it is up to the gardener to grow or throw this plant.

Photo by Deborah Maier.


Stinkweed (Thlaspi arvense)

Stinkweed is an annual or winter annual in the Brassicaceae family that is known for its unpleasant sour, turnip-garlic like odor when crushed. It grows up to 0.6 metres on a smooth, erect, and sometimes branched stem in almost any disturbed soil. Smooth, oblong, alternate leaves form a rosette on the lower plant, while upper leaves clasp the stem. It produces racemes of small, white petaled flowers which mature into distinctive rounded seed pods. The seeds have a broad winged border and become yellow to greenish-orange as they mature. The heavy seed-coat allows them to stay viable in the soil for up to 20 years. Stinkweed is a prolific reseeder, with seed dispersal through wind, water, and animals. Seeds will germinate throughout the growing season and this weed can quickly outcompete garden crops if left unchecked. Immature seedlings can be turned under, mature plants should be pulled and discarded in the trash.

Photo by Deborah Maier.

Tansy, common (Tanacetum vulgare)

The common tansy is originally from Europe, and it was introduced to North America for medicinal purposes. The plant has yellow flowers in the shape of a button and can grow up to 1.5 metres in height. Its stems are branched and have a purple tint to them. The common tansy outcompetes native plants and produces a toxic compound that harms wildlife and cattle when ingested. Therefore, it is recommended that this plant is thrown. Mowing areas with common tansy, the use of chemical control, and the planting of native vegetation can help stop the spread of the weed. For more information, please follow the link. Nature Conservancy: Common Tansy 

Photo by Deborah Maier

Yellow sweet clover (Melitotus officinalis)

Yellow sweet clover is a biennial plant, so it has a two-year life cycle. It is a plant that develops wide deep root systems. It has a tall stem with yellow flowers and toothed leaves, and typically grows up to a metre in its first year of growth. The flowers and plant material have a sweet fragrance. Yellow sweet clover improves the structure of soil, fixes nitrogen and attracts pollinators such as bees, hence why it is recommended that this plant should be grown.

Photo by Deborah Maier. 

Thank you to our volunteers and Master Gardener Program students for researching the information posted on this page.

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