Potentilla norvegica

Potentilla norvegica, known in English as "rough cinquefoil" or "Norwegian cinquefoil" and in French as potentille norvégienne or potentille de Norvège, is an annual, biennial, or short-lived perennial native to the temperate northern hemisphere. The dainty yellow flowers have five petals, and five sepals which are longer than the petals and protrude between them. Despite the English common names ("cinquefoil" means "five leaves"), the compound leaves have three leaflets rather than five. If you click the photo to enlarge it you will see they, and the stems, are covered with fine hairs.

Erigeron philadelphicus

Erigeron philadelphicus, known in English as "Philadelphia fleabane" and in French as érigéron de Philadelphie is a biennial or perennial native to most of North America. I photographed this plant at Riverdale Farm.

Hesperis matronalis

Warning: this is a very invasive plant in southern Ontario Hesperis matronalis, known in English as "dame's rocket", "damask violet", "dame’s violet", "dames-wort", "dame’s gillyflower", "night-scented gillyflower", "queen’s gillyflower", "rogue’s gillyflower", "summer lilac", "sweet rocket", "mother-of-the-evening" or "winter gillyflower", and in French as julienne des dames is a biennial or short-lived perennial native to Eurasia. It can be distinguished from similar-looking phloxes by the four petals (phlox has 5 petals).

This is a very pretty flower, and it is easy to see why some gardeners allow it or even encourage it in their gardens. Unfortunately, here in southern Ontario dame's rocket is seriously invasive. According to Invasive Exotic Species Ranking for Southern Ontario, dames rocket is a Category 1 invasive (the worst category, like the dreaded garlic mustard). They describe Category 1 species as follows:

Aggressive invasive exotic species that can dominate a site to exclude all other species and remain dominant on the site indefinitely. These are a threat to natural areas wherever they occur because they can reproduce by means that allow them to move long distances. Many of these are dispersed by birds, wind, water, or vegetative reproduction.

These are the top priority for control, but control may be difficult. Eradication may be the only option for long-term success.

Similar-looking alternatives for Toronto gardeners include Phlox pilosa (native) or Phlox paniculata (not native, but not invasive and widely available).

Descurainia sophia: foliage

Descurainia sophia, known in English as "flixweed", "flixweed tansymustard", "herb Sophia", or "pinnate tansymustard", and in French as sagesse des chirurgiens, sisymbre sagesse, or sisymbre sophia, is an annual or biennial native to Eurasia. At this stage of development, it looks very similar to the native D. pinnata; later on it can be distinguished by its seedpods.

Geranium robertianum: foliage, flowers, and unripe seedpods

Last year I cheated and included a photo of this pretty native taken outside of Toronto (in my hometown of Almonte in eastern Ontario). I was so happy to discover it growing in a flowerbed at East Lynn Park (on the Danforth near Woodbine) (surrounded by invasive Vinca minor, alas).

Alliaria petiolata: flowers and seed pods

Warning: this is an extremely invasive plant in Toronto.

Yes, I know, this is my third post about garlic mustard in May, but this is the first time I've shown the fully opened flowers and nefarious seed pods of this plant. Here you can see how garlic mustard practically forms a monoculture. (Photo taken in High Park, south of the Black Oak Café).

Here's a close-up of the flowers and seed pods. If you missed it, or if you aren't convinced that this plant should be uprooted on sight (at least in North America), reread my post about why garlic mustard is horrible. Then read Sarah's article, Top 10 Reasons to Search and Destroy Garlic Mustard. Then if you still aren't convinced, google it and see why experts agree this plant does not belong here in North America.

Alliara petiolata: flower buds

This is an extremely invasive species in Toronto. Although I just posted a whole long thing about why garlic mustard is evil, I haven't posted a picture of the flower buds. I was disheartened to see it's that time of year again already. Photo taken at Wilket Creek Park.

Alliaria petiolata: foliage

This is an extremely invasive species in Toronto. Alliaria petiolata, known in English as "garlic mustard" and in French as alliaire officinale ou herbe à ail is a biennial native to Eurasia and northern Africa. It is one of the worst invasive plants in Toronto.

Garlic mustard was originally brought to Canada from Europe as a food plant. Unfortunately, it has flourished too well. Garlic mustard is not edible to Canadian wildlife, it emerges early in the spring before many native plants, it produces large numbers of seeds, and it harms mycorrhizal fungi that native plants need to grow properly. These factors give it an advantage over native plants, with the result that it can invade forests and outcompete them. There are areas of the forest in High Park that are completely overrun with garlic mustard, at the expense of native plants. Garlic mustard is invading the forest around the Ontario Science Centre as well, endangering their beautiful white trilliums. Because Canadian wildlife won't eat garlic mustard, replacing native plants with garlic mustard means less food for wild animals and therefore a loss of animal as well as plant biodiversity.

For these and other reasons it is important for Toronto gardeners to be able to recognize garlic mustard and remove it. In the first year, garlic mustard forms a low rosette of heart- or kidney-shaped leaves with a jagged edge. The leaves have a distinctive garlicky smell when crushed. In the second year, the plant produces a stem 30-60 cm tall with clusters of small, white, four-petalled flowers. The flowers are followed by skinny upright seed pods, but please don't let it get to that stage if you can help it. After setting seed, the plant dies, which is good news. (There are some good photos of garlic mustard leaves, flowers, and seed pods on this page by the Plant Conservation Alliance Alien Plant Working Group.)

To control garlic mustard, remove the entire plant in the first year, or remove at the very least the flowers in the second year (in erosion-prone sites you may want to leave the roots of second year plants in place, but cut the plants off close to the ground, otherwise more flowers can form in the leaf axils). Don't leave the flowers or unripe seedpods lying around as even if cut off from the root they can still ripen and produce viable seed. You can eat the plants if you like; here's a recipe for garlic mustard pesto (I haven't tried it myself yet).

Garlic mustard seed in the soil remains viable for years, so eradicating it is a long-term project. So let's make it a May tradition to enjoy a walk outside eradicating garlic mustard!

Verbascum thapsus: leaves

Don't plant this—it's invasive!

Verbascum thapsus, known in English as great mullein or common mullein, and in French as molène thapsus, molène Bouillon-blanc, Bouillon-blanc or Bouillon jaune is a biennial native to Eurasia and north Africa. In Canada it is generally considered a weed, and a number of sources call it invasive.

Here you can see some of the old foliage from last year, and a rosette of new leaves opening in the middle. The soft velvety leaves are rather nice, but do we really need more of this plant spreading itself around and invading wild spaces, where it displaces native plants?

Petroselinum crispum: at winter's end

Petroselinum crispum, known in English as parsley and in French as persil, is a common biennial herb native to the Mediterannean.

I never thought of parsley as an evergreen, but it has stayed a bright green through the winter, despite having spent months crushed under snow!

Rudbeckia hirta: seeds

Rudbeckia hirta, known in English as black-eyed Susan, gloriosa daisy, or yellow ox-eye daisy, and in French as Rudbeckie dréssé is a biennial native to most of North America. Its daisy-like flowers have bright golden yellow rays surrounding dark brown cones in the wild type, though many cultivars with various colourings are available.

I collected these seeds from my landlords' garden; the parent plants came from seed given out by the High Park Nature Centre for Earth Day 2007.

Geranium robertianum: flowers

Geranium robertianum, known in English as herb Robert, redshank, bloodwort, fox geranium, or red robin, and in French as herbe à Robert, is an annual or biennial native to North America. Unlike the plants commonly known as "geraniums" (which are really Pelargoniums), this wild geranium has finely divided somewhat fern-like leaves and single dainty five-petaled pink flowers.

I suppose it's cheating to include this photo in this blog as it was taken in Almonte, in eastern Ontario, rather than Toronto, and growing wild rather than in a garden. But it certainly could be grown in Toronto gardens...

Rudbeckia hirta: flowers

Rudbeckia hirta, known in English as black-eyed Susan, gloriosa daisy, or yellow ox-eye daisy, and in French as Rudbeckie dréssé is a biennial native to most of North America.

These gorgeous flowers grew from seed I received for free from the High Park Nature Centre for Earth Day 2007. I threw them around in the garden but wasn't sure anything had grown until the second year, when suddenly there were big beautiful plants covered in blooms. It's amazing to me that one tiny seed can produce a 40-cm tall plant with 50 flowerheads on it. Each flowerhead lasts a long time; the flowerhead in the foreground, with a flatter centre that's light in the middle, is a younger bloom; as the blossoms age the centres become darker and more conical as seen in the background.

Bees love these flowers!