Category Archives: Herbarium

Asclepias – Milkweed

by Adriana Lopez-Villalobos and Amelie Mahrt-Smith

If you’ve ever thought of planting flowers to attract pollinators to your garden, milkweed should be on top of your list – plants in the genus Asclepias are known for attracting all kinds of insects, most notably the monarch butterfly. The common milkweed, A. syriaca, is estimated to provide food to over 450 different species of insects! [3] Asclepias is a member of the Apocynaceae family, also known as the dogbane family. While they may provide adequate food for pollinators, some taxa are poisonous to animals – the family gets its colloquial name from those taxa that were historically used as dog poison [6]. The genus name, Asclepias, comes from the Greek god Asklepios the god of medicine. Milkweed has had a variety of uses in human culture over the years; medicine is just the beginning.

Common milkweed, Asclepias syriaca, growing by a riverbank in Kingston, ON.

The flowers of Asclepias are morphologically distinct. They are clustered in heads called umbels, with 30-50 individual flowers in each. The image below shows a close up of several A. syriaca flowers and their characteristics. The petals (a) are reflexed downward toward the stem, and a petal-like shape is made by the corona, which is made up of five nectar-secreting hoods (b) and incurving horns (c). The floral corona helps to attract pollinators. Pollen is produced in the anther (d) and received by the stigmatic disc (e). In Asclepias, these structures are fused into a single structure called the gynostegium. Between two adjacent anthers forms the anther wings (f), which enclose a stigmatic chamber. Above this chamber is the pollinium gland (g), where pollen can be retrieved[4]. All of the flower buds in an umbel will open within 2-3 days of each other, and fade in colour and begin to shrivel shortly after being pollinated [5]. Not every flower will produce seeds, even if they have been pollinated – one stem may have 50 flowers but still only produce one or two seed pods.

LEFT: Close up of A. syriaca inflorescence, showing the different parts of the individual flower. RIGHT: Seed pods ripening on an A. syriaca individual.

Pollinators searching for nectar on the unstable flowers can get pollinia, a mass of pollen grains, stuck to the adhesive pads on their feet that help them climb. These pollen grains may be deposited on the stigmatic disc of another flower as the insect continues to forage [4]. While they are visited by bumblebees, wasps, ants, and flies as well, milkweed is most commonly associated with the butterflies that are attracted to the sweet-smelling flowers. The iconic monarch butterfly relies on milkweed for its entire life cycle. The eggs are laid on the underside of milkweed leaves, which the caterpillars eat from when they hatch. The poisonous compounds in Asclepias, chemicals called cardiac glycosides, are actually used by the caterpillars as a defence mechanism against predators. Insects like the monarch caterpillar that are adapted to feeding on Asclepias plants store these compounds in their body instead of metabolizing them, which effectively makes them poisonous to those looking for a tasty grub to snack on [1]. After metamorphosis, the monarch butterfly may eat the nectar from milkweed flowers in addition to many other species, but it will always return to milkweed to lay its eggs.

Although toxic in large quantities, the compounds in milkweed have given them traditional medicinal uses in human culture. A. syriaca, the common milkweed, was used by colonial settlers as an expectorant, an emetic, and a remedy for asthma. A related plant, A. tuberosa, has been used to induce perspiration and in the treatment of lung ailments. The milky latex produced by the plant, which can be seen oozing from the stem if one breaks off a leaf or flower, was investigated as a rubber precursor but was never profitable. The seed hair fibres were used as a wartime substitute for kapok to make life jackets [2]. Although not profitable for humans, milkweed is still a very important plant for pollinators like the monarch butterfly.

Asclepias syriaca is native to North America and is commonly found invading fields and roadsides. This specimen was collected at QUBS in 1960 by the former curator, Roland Beschel. You can find A. syriaca in flower all around QUBS from July to early August!

A specimen of A. syriaca collected at QUBS in 1960.


  1. Lewis, D.R. Iowa State University. The Milkweed Insects.,feed%20on%20the%20common%20milkweed.&text=Plants%20can%20be%20interesting%2C%20especially,seeing%20them%20eaten%20by%20insects. Downloaded on 03 August 2020.
  2. Simpson, M.G. 2010. Plant Systematics., 2nd. Ed. Academic Press, Elsevier. ISBN 9780123743800
  3. Moore, R.J. 1946. Investigations on rubber-bearing plants. V. Notes on the flower biology and pod yield of Asclepias syriaca L. Can. Field Natur. 61: 40 – 46.
  4. Macior, L.W. 1965. Insect adaptation and behavior in Asclepias pollination. Bull. Torrey Bot. Club, 92:114 – 126.
  5. Gaertner E.E. 1979. The history and use of milkweed (Asclepias syriaca L.). Economic Botany 33: 119-123.
  6. Erickson, J.M. 1973. The utilization of various Asclepias species by larvae of the monarch butterfly, Danaus plexippus. Psyche A Journal of Entomology 80(3) DOI: 10.1155/1973/28693

LAMIACEAE – The Mint Family

by Adriana Lopez-Villalobos and Amelie Mahrt-Smith

Fans of alternative medicine are likely familiar with the mint family, the Lamiaceae. Many of these plants produce essential oils used to battle ailments or boost the immune system – for example, oil of oregano is a common herbal treatment for sore throats, and peppermint oil has a cooling effect that can alleviate sore muscles. Lamiaceae plants are also widely used to add flavour to dishes and drinks, such as sage and rosemary – both in the genus Salvia. Among the other curious properties of the plants in this genus, Salvia divinorium (sometimes known as sage of the diviners or simply Salvia) is psychoactive and is recreationally smoked, chewed or consumed as a tea to induce hallucinations.

There are a variety of chemical compounds responsible for the different properties of plants in the Lamiaceae family. Within the Nepetoidae subfamily, which contains many of the more familiar Lamiaceae plants, the phenolic compound rosmarinic acid is mainly responsible. It was named after the plant from which it was first isolated, Salvia rosmarinus, also known as rosemary. This acid has shown antiviral, antimicrobial, and antioxidant activities. It has also been reported to deter pests like the tobacco hornworm (Manduca sexta).(4) Plants containing rosmarinic acid are most used to treat inflammation – and advances in molecular genetics help to explain why they are effective. In basic terms, rosmarinic acid stops the production of compounds that initiate inflammatory responses when cells are under stress – for example, from a viral infection. The acid inhibits the genes that tell the cell to make inflammation-inducing compounds and thus eases the symptom.(2)

Unsurprisingly, the Lamiaceae have been used in traditional medicine around the world for generations. The common characteristics of this family may have helped early peoples to recognize that a variety of different species can be used for food and medicine – the resemblance between species is strong, especially as you move from the family to the subfamily or to the genus level. Plants in the mint family usually have simple leaves, and they are always oppositely arranged. The stems are usually four-angled, with the leaves at each node being rotated 90° so that the leaves grow in four directions away from the stem. The flowers, which can be hermaphrodite or functionally female (i.e. The male parts are sterile), usually have five lobes and two ‘lips’ – hence the synonym Labiatae which is sometimes used to describe this family. The plant itself often has dense glands and a strong aroma.(3) Using these characteristics, you can identify common plants in the mint family that may be growing around your neighbourhood!

Glechoma hederacea – Ground Ivy

A native to Europe, G. hederacea is a creeping herb that was brought over deliberately by settlers for medicinal use and food and it quickly invaded the North American lands. It is low to the ground and inconspicuous – it can be recognized by its oppositely arranged, kidney-shaped leaves with blunt teeth, and blue-violet flowers about ½ inches long. It flowers in late spring and early summer, and by this time of year has already set seed. The upper lip of the corolla has three lobes that appear to be three distinct petals; the lower lip has two lobes with spots that are usually purple but occasionally pink or white. It flowers early in spring, and by mid-summer has produced seeds. However, it spreads much more rapidly by producing clones than seed dispersal. It is also suspected to have allelopathic effects, which helps it outcompete other plants and rapidly take over an area.(1)

Glechoma hederacea is a member of the Nepetoideae subfamily, so the presence of rosmarinic acid and other chemical compounds makes it a good contender for medicinal use. It is an effective anti-inflammatory agent and as such has been used against catarrh, the excess buildup of mucus caused by inflammation of the body’s mucus membranes.

Prunella vulgaris – Self-heal

Named for its ubiquitous use in traditional medicine, the selfheal is a Holarctic species – native to the continents of the northern hemisphere. It is also a member of the Nepetoideae subfamily and contains rosmarinic acid as the major phenolic compound. It has been said to treat sore throats, fevers, and accelerate wound healing.(5) Prunella vulgaris has also been shown to have specific activity against herpes simplex virus (HSV). Chemical compounds produced by the plant are shown to be effective at reducing the viral load of cells infected with HSV and has the potential to be used as an antiviral treatment for cold sores.(6)

The leaves are lance-shaped and entire, arranged oppositely as is typical of the Lamiaceae. The flowers are violet or purple and found in short spikes. It flowers from late spring to fall and can be found along roadsides and in waste places throughout Kingston, ON right now!

Because of the widespread medicinal and culinary uses of plants in the Lamiaceae family, European colonists brought many of them around the world with them. In addition to intentional introductions, seeds and fragments of plants can hitchhike along with other biological materials brought by settlers. For example, Lamium amplexicaule, also known as common dead-nettle is one of many members of the Mint family that was introduced to North America from the Old World. This specimen was collected in Kingston by George Lawson in 1859. Lawson was appointed professor of Chemistry and Natural History at Queen’s University in 1858, where he set up a botanical laboratory. He was also a founding member the Botanical Society of Canada, established in 1860. His wife, Mrs. Lawson, was an amateur botanist, and inspired equal privileges for female members of the Society. He was an ambitious man and saw the Botanical Society as a means of encouraging botanical research beyond the British settlements in Canada.(7) Although he only stayed a few years at Queen’s before moving on to Dalhousie University, his legacy remains at Queen’s in the specimens that are kept within the Fowler Herbarium.


  1. Hutchings, M. J., and E. A. C. Price. 1999. Glechoma hederacea L. (Nepta Glechoma Benth., N. hederacea (L.) Trev.). Journal of Ecology 87:347 – 364.
  2. Kim, J., S. Song, I. Lee, Y. Kim, I. Yoo, I. Ryoo, and K. Bae. 2011. Anti-inflammatory activity of constituents from Glechoma hederacea var. longituba. Bioorganic & Medicinal Chemistry Letters 21:3484 – 3487.
  3. Kokkini, S., R. Karousou, and E. Hanlidou. 2003. Herbs of the Labiatae. Pages 3082 – 3090 in L. Trugo, and P. M. Finglas, editors. Encyclopedia of Food Sciences and Nutrition (Second Edition). Academic Press.
  4. Petersen, M., and M. S. J. Simmonds. 2003. Rosmarinic acid. Phytochemistry 62:347 – 364.
  5. Psotoyá, J., M. Kolář, J. Soušek, Z. Švagera, J. Vičar, and J. Ulrichová. 2003. Biological activities of Prunella vulgaris. Phytotherapy Research 17:1082 – 1087.
  6. Xu, H., S. H. S. Lee, S. F. Lee, R. L. White, and J. Blay. 1999. Isolation and characterization of an anti-HSV polysaccharide from Prunella vulgaris. Antiviral Research 44: 43 – 54.
  7. Zeller, S. Lawson, George. 2003. In Dictionary of Canadian Biography, vol. 12, University of Toronto/Université Laval,– accessed online on July 20th, 2020.

The Asteraceae Family

by Adriana Lopez-Villalobos and Amelie Mahrt-Smith

The Asteraceae, also known as the aster, daisy, or sunflower family, is the second largest family of flowering plants – and it shows. All over Kingston this week, various Asteraceae species are showing off their unique flowers. The radial petals of Asteraceae heads play tricks on our eyes, making them appear as one big flower. In reality, these heads are made up of many, very small perfect ‘disk flowers’ surrounded by a ring of “ray flowers” (Image 1).

What appears to be petals are individual ray flowers, which sometimes have no reproductive parts.

closeup of an individual flower of Tripleurospermum inodorum
Image 1: A closeup of an individual flower of Tripleurospermum inodorum. Try bringing a magnifying glass out with you to get up close and personal with some Asteraceae flowers!

A common pattern of Asteraceae flower heads is the rows of bracts below the ray flowers. Bracts are modified leaves that resemble sepals and that sit beneath the ray flowers (see Image 2). Perfect flowers would often have only one sepal per petal, but asters can have several layers of bracts. While this is not a foolproof test, this is one of the characteristics that can be used to identify aster flowers.

Modified leaves on a T. inodorum flower head
Image 2: Modified leaves, together called the involucre structures on a T. inodorum flower head are the bracts, forming two distinct rows.

Check out the Asteraceae species that we found decorating Kingston’s green spaces this week!

Looking at the images above you might be wondering:

Are there ray flowers in pineapple weed?

Where are the discs flowers in chicory and dandelion?

Do all aster flowers have disc and ray flowers?

If you had questions like this, you are very observant! Not all the aster flowers have the same structure, so let us consider some of the kinds of composite flower you might encounter.

First, notice how the heads are configured in terms of disc and ray flowers. Usually, you will come across three basic flower-head types:

  1. Heads composed of only ray flowers (also called ligulate flowers), as in dandelion, chicory (“a” and “c” in image above), endive, and wild lettuce.
  2. Heads composed of only disc flowers (also called discoid), as those found in species of the genus Eupatorium, Ageratum, Cirsium (thistles) and Arctium burdock (“e” in image above, also see below).
  3. Heads composed of both disc and ray flowers are called radiate flowers. They have disc flowers tightly packed together in the head’s “eye,” while enlarged ray flowers that function as petals radiating outward from the eye. Species in this group include sunflowers, Black-eyed Susans, chrysanthemums, dahlias. In some flowers of the genus Zinnia, the yellow, five-lobed disc flowers in the head’s center are clearly visible, surrounded by red ray flowers, which most people would incorrectly call “petals.”

We love aster flowers! We decided to change the format of our blog post this week to give you an overview of more than one or two species. Identifying species in the Asteraceae family could turn into a complicated puzzle, and for many botanists, this is what attracts them!

To help us learn the different common species you might observe around Kingston or QUBS, without making it overwhelming, it is important to put them into larger botanical categories. These categories are called subfamilies. The species we have observed over these last weeks, and the ones we are describing in this week’s blog post, fall into three subfamilies: Chicorioideae, Carduoideae and Asteriodeae. Learning the characteristics associated with larger categories (in this case subfamilies) will help you to recognize species out in the field by association – so let’s delve right into it.

Subfamily: Chicorioideae

Commonly known as the chicory subfamily, these plants have no disk flowers, only ray flowers. The rays may overlap all the way to the centre of the flower head. The stems contain a milky juice, which gives them a bitter taste. They are edible and used in folk medicine as a digestive aid, among other uses. All three of the species highlighted here are introduced from Europe. Common species in this family around QUBS land base are: Pilosella aurantiaca (syn =  Hieracium aurantiacum) and Pilosella caespitosa (syn = Hieracium caespitosum). These plants are commonly known as Hawkweed.

a. Taraxacum officinale (common dandelion) 

This abundant weed is familiar to most – the ‘blowballs’ formed by the ripe seeds were bringers of wishes in childhood. The bright yellow flowers, 1-2” wide, crop up from spring until fall on hollow stems. The irregularly lobed leaves are attached at the base. The roots, when roasted, are said to make a flavourful coffee substitute.

b. Tragopogon pratensis (yellow goat’s beard)

The flowers of goat’s beard may resemble dandelion heads on a tall stalk, up to 3 feet high. However, they are only open in the early morning light, hence the alternate common name for this species: Jack-go-to-bed-at-noon. The leaves are grass-like, alternate, and clasp the stem. The leaves are edible, it is slightly bitter, as is the root. The plant is biennial – it takes two years to complete its life cycle, and it turns woody in the second year. The genus name comes from the Greek word tragos. “goat,” and pogon “beard.”

c. Cichorium intybus (chicory)

Part of the endive genus, the chicory plant sports light bluish-purple flowers along its branches. Petals are toothed at the end. The entire plant can reach up to 4 feet (1.2 meters) tall. The leaves are edible, and some species of Cichorium are cultivated for salad greens. Blanching the leaves can reduce their bitter taste. Cichorium is the latinized Arabic name for chicory. The species name intybus comes from the Egiptian word tybi, “January” which is the month in which chicory is traditionally harvested. Common chicory species widely used for food includes the radicchio, puntarelle, and Belgian endive.

Subfamily: Carduoideae

Also known as the thistle or artichoke family. Most of the plants in this group will have some prickly parts, usually the leaves. These are characterized by sharp prickles on their edges, which protects them from herbivores. The plants in this subfamily have their flowerheads protected inside a tight wrapping of bracts, like an artichoke, which by the way belong to the genus Cynara. Cornflowers (Centaurea cyanus) is also a member of this subfamily.

d. Centaurea jacea (brown knapweed)

The brown knapweed is a common ornamental garden species, because its purple, funnel-shaped ray flowers are particularly eye-catching. There are several rows of brownish bracts, which distinguishes it from the black knapweed (characterized by blackish bracts). The petals of the rays attract pollinators like bees, flies, and butterflies and direct them to the disk flowers in the centre. This species was also introduced from Europe.

e. Arctium minus (common burdock)    

Common burdock is introduced across most of North America but this species is native to Europe and Asia. This species is commonly found in many places in Kingston: backyards, parks, waste grounds, rail-way grades and roadside. The taproots and young shoots are edible. The taproots are widely used in herbal medicine and are considered by some to be effective against skin conditions, infections, and in removing heavy metals from the body. The genus Arctium comes from the Greek word arktos, “bear,” a possible reference to the rough-textured bracts. The species name minus means “smaller.”

Subfamily: Asteriodeae

This subfamily is further divided into several tribes (more useful for ID purposes compared to tribes in other subfamilies), one being the Anthemideae (Chamomile) tribe. The plants in this tribe are odorous, and many have been used in traditional medicine (like chamomile tea, a well-known herbal sleep remedy). Another characteristic of this tribe is the bracts, which are thin, dry, and translucent.

f. Matricaria discoidea (pineappleweed)

This wildflower, at first glance, does not look much like its chamomile cousins. It grows low to the ground, with the typical yellow disk flowers in heads but lacking rays. In fact, the species name discoidea, means “without rays, disc-like”. Pineapple weed gets its name from the citrusy smell it gives off when crushed. The fresh plant is edible and makes a nice mild tea that has been used to treat stomach pains, colds, and fevers. This species is native to North America!

g. Achillea millefolium (common yarrow)

It is said that the warrior Achilles used a poultice of yarrow to stop bleeding during battle, which may be where the Achillea genus got its name. It is an astringent, as well as a diuretic and diaphoretic. Yarrow is a North American native, recognizable by small clustered flower heads each with 4-6 rays and several disk flowers in the centre. The petals can be white or pink. The leaves have a lance-shaped outline but are divided into many fine segments.


h. Tripleurospermum inodorum (scentless chamomile)

Chamomiles have daisy-like flowers, with white rays and yellow disks. The leaves are finely divided and may be scentless (as in T. inodorum), or strongly scented. It was previously placed in the Matricaria genus with pineapple weed. Despite its name, this species is not one of the commonly used varieties for making chamomile tea.

i. Leucanthemum vulgare (oxeye daisy)

The oxeye daisy bears strong resemblance to the chamomiles; long-stalked white flower heads and yellow disks. They can be differentiated by the leaves, which are slender and toothed as opposed to the finely divided leaves of chamomiles. They also usually bear a single flower head per stalk, whereas chamomiles may have several branches. It is considered an invasive species in parts of North America where it has been introduced.

Also, within the Asteriodeae subfamily is the Astereae tribe, which contains one of our native common North American asters.

j. Erigeron annuus (daisy fleabane)

This daisy-like wildflower is characterized by many rays – usually more than 40. These rays can be white or pinkish. The leaves are distinctively toothed, and the stem is hairy. Daisy fleabane is a pioneer species, which means it is one of the first plants to colonize a new or recently disturbed area. The genus name Erigeron comes from the Greek words eri, “early,” and geron, “old man” a reference to some species flowering and setting fruit early in the growing season.

Asteraceae in the Fowler herbarium.

We have not fully digitized all the cabinets that contain the specimens of this family, however with the incredible work of volunteers Donna and John Greenhorn, undergraduate students Elizabeth Garland (Honours thesis at Dr. Lonnie Aarssen lab 2018), Mahsa Aghaeeaval (SWEP 2019) and Amelie Mahrt-Smith (SWEP 2020), and all the amazing Queen’s volunteers that helped transcribed specimen labels, the database has 374 specimens from more than 30 species. Specimens from Tragopogon, Cirsium, Erigeron, Arctium, Centaurea, Carduus, Grindelia, Bidens, Sonchus, Erechtites and more represent some of the diversity of Asteraceae specimens fully digitized in our collection. Some of the oldest specimens from this family are of Tragopogon pratensis (yellow goat’s beard). We have specimens collected in Kingston since 1831, as part of the original collection of James Fowler. The herbarium also houses specimens across a broad range of localities – Asteraceae species have been collected in eight of the Canadian provinces and five American states. Specimens of bull thistle, Cirsium vulgare, have been donated to the herbarium from Ontario, Quebec, Nova Scotia, New Brunswick, British Columbia, and Alberta! The one below was collected by Queen’s student Annie Boyd in 1897. You will likely see these prickly plants in flower later this summer. Check out the beautifully prepared Erigeron annuus specimen collected in the former Pittsburgh Township, now amalgamated into the city of Kingston (as of January 1, 1998) by Assistant Curator A.E. Garwood. He was a self-taught botanist and naturalist, accountant by profession, and a key member and one of the most prolific contributors of the Fowler herbarium during the 90’s. He worked closely with curators Ronald Beschel and Adele Crowder, and other important collectors such as, C.H. Zavitz, S. VanderKloet, R. Hainault, Good M., and Ian Macdonald. Look at the T. pratensis specimen collected by Ian Macdonald and note the differences on the amount and quality of information included on the labels. What do you observe? Can you draw any conclusions regarding the collection methods, the mounting of specimens and the value of data?


  • Elpel, T.J. 2004. Botany in a Day: The patterns method of plant identification. An herbal field guide to plant families of North America. HOPS Press, LLC, 6th edition. Pp 163-174.
  • Dickinson R. and Royer F. 2014. Plants of Southern Ontario: trees, shrubs wildflowers, grasses, ferns, and aquatic plants. Lone Pine Publishing. Pp 370 – 409 year
  • Niering W and N. Olmstead. 2001. National Audubon Society. Field Guide to Wildflowers. Eastern Region. Revised by Thieret W. John. Chanticleer Press, Inc.
  • Peterson Lee. Field guide to edible wild plants of eastern and central North America. Houghton Mifflin company, Boston NY.
  • Newcomb, L. 1977. Newcomb’s Wildflower Guide. Little, Brown and Company. New York.

RANUNCULACEAE – the buttercup family

by Adriana Lopez-Villalobos and Amelie Mahrt-Smith

The Ranunculaceae family is more commonly known as the buttercup family, which is reminiscent of some of the shiny yellow members of the Ranunculus genus. The buttercup family may be considered “simple” from an evolutionary standpoint, because the floral parts – the petals, sepals, stamens and pistils – are all distinct and not fused in any way. Moreover, reproductive parts are often of an indefinite number as compared to other plant families with predictable numbers of three, four, or five. Some flowers, such as in the columbine, delphinium and clematis have flowers that might look highly complex, but they are still considered “simple” because all the parts are independently attached. There is quite a bit of variation in this family in terms of the number of sepals (3-15), petals (0-23), and stamens; however, for identification, one common pattern to look for is the multiple pistils (3 to more) in the centre of the flower, each with its superior ovary (hypogynous). Some members of the Rose family also have multiple pistils, but they have a hypanthium, a cuplike structure from which the sepals, petals and stamens all arise (perigynous flowers). The leaves are also different in that the roses will often bear prominent stipules, a feature lacking in the Ranunculaceae (Elpel, 2004). For examples of these differences click | here |.

Over the last few weeks, we have seen several examples of species from this family in Kingston. This week we decided to give a turn to two species native to Canada: the red columbine and the Canada anemone.

Aquilegia canadensis (Canada columbine)

A garden favourite, this member of the Ranunculaceae family is native to North America! Aquilegia canadensis, also known as the red columbine, wild columbine, or Canada columbine in English, is probably more familiar as a colourful addition to a carefully tended garden than as a weed. Outside of the city, you may be able to find this short-lived, spring-flowering perennial plant on rocky outcrops, dry woods, slopes, ledges or open areas, but in urban areas like in Kingston, it has been mostly crowded out of untended space by more competitive invasive species like garlic mustard (Alliaria petiolata; see our Blog post from June 9th, 2020). It has been suggested that the name Aquilegia is derived from the Latin word Aquila, meaning Eagle, possibly because of the flower’s spurs’ resemblance to an Eagle’s talon.


Aquilegia canadensis along sidewalk
Aquilegia canadensis amongst the foliage in Kingston, ON.

Columbine flowers are showy and unique, each petal having a long narrow spur at the back. The leaves grow in leaflets of 3 with deep lobes. The Canada columbine can be differentiated from similar columbine species like the European columbine (A. vulgaris) by its scarlet flowers with a yellow centre, and its stamens, which are long and protrude from the flower; the European columbine’s flowers are typically blue, purple, or white, and their stamens are not protruding (Newcomb 1977). Canada columbines can grow in a wide range of well-drained soil and can tolerate moderate shade. As well, this species is said to have good resistance to leaf miner beetles, which often cause damage to other species of columbines. For some tips on growing A. canadensis in your garden, as well as a shortlist of some other columbine species native to Canada, see | here |

Two species of Aquilegia
Left: Aquilegia canadensis, native to North America; Right: Aquilegia vulgaris, the garden cultivar introduced from Europe.

The columbine flower produces nectar in its spurs, which attracts a variety of pollinators, including the ruby-throated hummingbird (Archilochus colubris). It is also a food source for the rusty-patched bumblebee, Bombus affinis, an endangered species of bumblebee native to Ontario whose numbers have declined due to several ecological factors, including habitat loss (Macior 1966). Although the rusty-patched bumblebee has not been seen in Ontario outside of the Pinery Provincial Park since 2002, there are many other native species of bumblebee that would appreciate some Canada columbines to snack on in your garden! This includes some threatened North American bumblebee species such as B. fervidus and B. pensylvanicus, as well as the hummingbird clearwing moth (Hemaris thysbe). Although it might seem logical to think that A. canadensis would reproduce primarily via outcrossing, genetic analysis using progeny arrays from populations across its range have shown that approximately 75% of its seed, on average, are the product of self-fertilization. Thus, Canada’s columbine has a mix-mating or selfing mating system, rather than outcrossing (Eckert and Herlihy 2004).

Queen’s Biology faculty member Dr Chris Eckert has investigated several aspects of A. canadensis life history, floral morphology, ecology and evolution; some of his research on A. canadensis conducted at the Queen’s University Biological Station can be found on the QUBS Research Projects website. In recent years, the genus Aquilegia has become a model system for the study of floral evolution and development because of its unusual floral morphology and the recent explosion in the number of species associated with pollinator shifts and other ecological factors. To take advantage of these features, a collaborative group has developed several genetic and genomic resources that have facilitated the study of the genetic basis of these morphological innovations (Kramer 2009).

Canada Anemone (Anemonstrum canadense)

The Canada anemone, or ‘windflower’, is an inconspicuous member of the Ranunculaceae family in flower this month. They are not quite as abundant in urban areas as some other introduced ranunculus species, such as the common or tall buttercup (Ranunculus acris), the creeping buttercup (Ranunculus repens), or other common garden escapees, but you may still stumble across this low white flower in the Kingston area. The name ‘anemone’ is an Ancient Greek word meaning ‘daughter of the wind’. Ironically, this species prefers sites protected from wind since strong winds can bend or break the thin flower stalks.

This species was, until recently, part of the Anemone sensu lato (in the broad sense) genus and is often still called by its synonym Anemone canadensis. However, recent molecular phylogenetic analyses revealed that there were many more species and genera that needed to be included in the genus to satisfy the criterion of monophyly. Instead of renaming hundreds of species and including morphologically different genera such as Clematis (virgin’s-bower), Pulsatilla or Hepatica, the Anemone genus was regrouped into several genera, one of them being Anemonastrum, where Canada anemone is currently placed (Mosyakin 2016).

Canada anemone
The Canada anemone along the wet, rocky shores of Lake Ontario in Kingston.

The leaves of the Canada anemone have 3-5 deep lobes and toothed edges, and they have long stalks that emerge from a clump at the base. The flowers are white with many yellow stamens in the centre bearing pollen that attract pollinators. The notable features of the flower are the white petal-like sepals, usually 5 per flower. Sepals are a division of the outer part of the flower called the calyx and are often green and resemble leaves; whereas petals are a division of the inner part of the flower called the corolla and are often showy and attract insects. In A. canadense there are only sepals (modified to look like petals) and the petals are absent.

closeup of the Anemone flower
A closeup of the Anemone flower – notice the five white sepals and numerous yellow stamens.

The Canada anemone typically inhabits river margins, low moist meadows,and thickets. In nature, it can be found growing in massive colonies, and in cultivated areas is a common garden escapee. It is distributed throughout southern Canada from Newfoundland to British Columbia and in the U.S from Maine to Montana south to West Virginia, Missouri, Kansas and scattered through the Rocky Mountains to New Mexico. It is a perennial that can grow in semi-shaded areas and makes a beautiful addition to gardens while also benefitting the ecosystem by supporting native pollinator communities! Keep an eye out for this wildflower throughout the summer months around Kingston, ON – it is more than just a weed.

Ethnobotanical and medicinal uses

A predominant property in the plants of the Buttercup family is an acrid protoanemonin glycoside oil. Most of the species are listed as poisonous, but most are safe to taste, as long as you spit it out! The buttercup taste is biting and acrid, and its strength varies between species. The acrid properties of the buttercups are unstable and are destroyed by drying or cooking, so the very mild buttercups are edible as salad greens or potherbs. Plants in the buttercup family have been studied for possible medicinal use since the 1900s. The chemical compound protoanemonin has irritant but also antibiotic properties. The Pawnee peoples of what is now Oklahoma used A. canadensis to treat headaches, and closely related species had medicinal uses ranging from topical wound care to reviving unconscious people (Turner 1984). A. canadense was used by many Indigenous peoples in medicine. Traditional knowledge about the plant’s properties and how to prepare them for medicinal use is paramount – one risks further discomfort and injury from improper use of traditional medicine. The Ojibwe, an Anishnaabe peoples who have inhabited the Great Lakes region for thousands of years, used A. canadense and other closely related species of Ranunculaceae as a poultice or wash to treat superficial wounds, as a remedy for colds and headaches, and for the revival of unconscious people (Turner 1984).

Using herbarium specimens to understand phenology

As the negative impacts of human activities on ecosystems become deniable, and more pressing to attend than ever, researchers need biological data spanning hundreds of years to understand how anthropogenic drivers affect biodiversity and natural resources. Changes in the timing of key life-history events, such as reproduction (flowering and fruiting) are among the most obvious and well-documented species responses to climatic change, especially for plants. In recent years, the scientific community has started to turn their attention to hundreds of millions of plants, fungal and animal specimens deposited in natural history museums as a potential source of these data. The increasing number of museum specimens becoming available online combined with newly developed web-enabled crowdsourcing platforms (i.e. CrowdCurio) and protocols for scoring and analyzing phenological data provide unparalleled access to ecological and evolutionary data spanning decades and sometimes centuries. Park et al. (2019) capitalized on the snapshots of phenology (i.e. flowering and fruiting) that herbarium specimens offer to increase the spatial, temporal and taxonomic diversity of phenological studies. They used 7,722 herbarium specimens from 30 flowering plant species with varying life-history traits, growth forms, native status and general reproductive seasonality (e.g. early- versus late-spring flowering), spanning 120 years and modelling to understand how phenology changes in response to climate change. Their study included the red columbine and Canada anemone!
Their results showed that early-flowering species flowered and fruited earlier in response to warmer spring temperatures and that the magnitude of these responses varies significantly between and within species across their latitudinal ranges. They also found that fruiting in populations from warmer, lower latitudes are significantly more phenologically sensitive to temperature than that for populations from colder, higher-latitude regions.

By bringing you these bits of information from the scientific literature we want to raise awareness of these unparalleled resources. Herbaria and natural history museums are under constant threat owing to budget cuts and other institutional pressures. Like the study by Parker et al. (2019), more publications out there are shedding light on the unique discoveries that are possible using museums specimens, and thus, pointing to the singular value of natural history collections in a period of rapid change.


  1. Eckert, C.G., Herlihy C.R. 2004. Using a cost-benefit approach to understand the evolution of self-fertilization in plants: the perplexing case of  Aquilegia canadensis  (Ranunculaceae). Plant Species Biology 19:159–173
  2. Elpel, T. J. 2004. Botany in a Day: The Patterns Method of Plant Identification. HOPS Press.
  3. Kramer, E. M. 2009. Aquilegia: A new model for plant development, ecology, and evolution. Annual Review of Plant Biology 60: 261 – 277.
  4. Macior, L.W. 1966. Foraging behavior of Bombus (Hymenoptera: Apidae) in relation to Aquilegia pollination. American Journal of Botany 53: 302 – 309.
  5. Mosyakin, S.L. 2016. Nomenclatural notes on North American taxa of Anemonastrum and Pulsatilla (Ranunculaceae), with comments on the circumscription of Anemone and related genera. Phytoneuron 79: 1 – 12.
  6. Newcomb, L. 1977. Newcomb’s Wildflower Guide. Little, Brown and Company. New York. pp. 228.
  7. Park D. S., Breckheimer I., Williams A. C., Law E., Ellison A. M., Davis C. C. 2018 Herbarium specimens reveal substantial and unexpected variation in phenological sensitivity across the eastern United States. Phil. Trans. R. Soc. B 374: 20170394.
  8. Turner, N.J. 1984. Counter-irritant and other medicinal uses of plants in Ranunculaceae by native peoples in British Columbia and neighbouring areas. Journal of Ethnopharmacology 11: 181 – 201.

Shepherd’s Purse – Capsella bursa-pastoris (Brassicaceae)

by Adriana Lopez-Villalobos and Amelie Mahrt-Smith

Image 1. Shepherd’s Purse, Capsella bursa-pastoris, growing between the cracks of the sidewalk on Garrett St. in Kingston, ON

Capsella bursa-pastoris may at first appear to be just another weed blending into the sea of fresh spring greenery. But take a closer look at this plant commonly known as Shepherd’s Purse, and you will notice the curious appendages from which it got its name. Its distinctive seed pods – small pouches in the shape of a heart – bear resemblance to an old-fashioned style of purse carried by shepherds in centuries past [6]. This widespread edible weed is a part of the Mustard family, Brassicaceae. This family is shared by garlic mustard (see our previous post about it), thale cress, and many common supermarket vegetables like broccoli and kale. Of the five species in the Capsella genus, C. bursa-pastoris is the only one found in North America, which makes it easier to identify this species in your community.

Image 2. Notice the large, irregularly lobed basal leaves and smaller, clasping stem leaves (left); as well, the small cluster of white flowers at the tip and the ‘purse-shaped’ seed pods emerging laterally from the stem (right).

Shepherd’s Purse is a cosmopolitan weed: it is found all over the world. Its secret weapon is its ability to grow in a wide variety of conditions. It can be found in disturbed ground or dumps, and frequently invades the cultivated soil in gardens and crops. It can grow in full sun or partial shade, dry or moist soils, and even cracks in concrete (Image 1); its hardiness makes it a good contender for urban living [3]. You can identify Shepherd’s purse by its large leaves with irregular lobes at the base of the stem, and smaller, arrow-shaped leaves that clasp the stem. In good conditions, it can reach 60-80 cm tall. Its tiny white clustered flowers have four petals each (with the 6 distinctive stamens: 2 outer short and the 4 inner long). The most identifiable feature is the heart-shaped seed pods attached to the main stem by a long stalk, which makes it distinguishable from similar plants like wild mustard (Image 2) [5]. Early in the spring, Shepherd’s Purse’s flowers begin to bloom, and they will continue to bloom until late fall. It is an annual, which means an individual plant only survives for one year, but several generations can be produced during the warmer months, and a single plant can produce up to 45,000 seeds! This is a high level of production that is facilitated, in part, by their ability to self-pollinate. Instead of waiting for an insect to come by and transfer pollen from one individual to another, the pollen simply fertilizes the flower from which it was produced (or a close neighbouring flower) [4].

Image 3. A Shepherd’s Purse plant collected in 1862, specimen is part of the Fowler Herbarium collection at QUBS. Click on thumbnail for larger image.

C. bursa-pastoris was introduced to North America by European settlers many times over. In the southwestern United States, it hitched a ride with Spanish colonizers, while further north in the U.S. and Canada, we have the British and French colonists to blame [7]. Shepherd’s Purse was once an important European medicinal herb, especially for women. Like many plants, has been overtaken by more effective modern drugs. All its parts are edible and can be used as a peppery seasoning – although we do not recommend you try this with unfamiliar plants! The leaves, which are high in vitamins and minerals, were traditionally made into a tea for the relief of pre-menstrual cramps and to reduce the risk of haemorrhaging after childbirth [1,2]. The Fowler Herbarium at the Queen’s University Biological Station has C. bursa-pastoris specimens collected in Kingston during the 1800s. This beautifully preserved Shepherd’s Purse specimen was collected in 1862 in the former township of Ramsay, Lanark County, which lies between modern-day Kingston and Ottawa. Notice the defining features of C. burasa-pastoris: the larger basal leaves, small stem leaves, heart-shaped seed pods, and clusters of tiny flowers at the tip (no longer white, but you get the idea.


  1. Aksoy, A., Dixon, J.M. and Hale, W.H. 1998. Biological flora of the British Isles. Capsella bursa-pastoris (L.) Medikus (Thlaspi bursapastoris L., Bursa bursa-pastoris (L.) Shull, Bursa pastoris (L.) Weber). Journal of Ecology 86, 171-186.
  2. Ghalandari, S., Kariman, N., Sheikhan, Z., Mojab, F., Mirzaei, M., and Shahrahmani, H. 2017. Effect of hydroalcoholic extract of Capsella bursa pastoris on early postpartum hemorrhage: A clinical trial study. J Altern Complement Med 23, 794‐799. doi:10.1089/acm.2017.0095
  3. Grieve, M. 1984. A Modern Herbal. Penguin. New York. ISBN 0-14-046-440-9
  4. iNaturalist. Shepherd’s purse. iNaturalist.
  5. Newcomb, L. 1977. Newcomb’s Wildflower Guide (pp. 150). Little, Brown and Company. New York.
  6. 6. Reader’s Digest Field Guide to the Wild Flowers of Britain. Reader’s Digest. 1981. p. 54. ISBN 9780276002175.
  7. Neuffer, B., and Hurka, H. 1999. Colonization history and introduction dynamics of Capsella bursa-pastoris (Brassicaceae) in North America: isozymes and quantitative traits. Molecular Ecology 8, 1667-1681.