- Written also: Canada Golden-rod, Canadian Goldenrod
- Family: Daisy Family – Compositae, subfamily Asteroideae
(formerly Aster Family – Asteraceae)
- Growing form: Perennial herb. Rhizomatous. Forms stands.
- Height: 30–150 cm (12–60 in.). Upper stem densely short-haired.
- Flower: Flowers form under 1 cm wide, single flower-like capitula surrounded by involucral bracts. Capitulum flowers yellow, ray-florets tongue-like; disk florets tubular, small. Stamens 5. Gynoecium composed of 2 fused carpels. Involucre round, 2–3 mm (0.08–0.12 in.) long. Involucral bracts overlap in many rows. Capitula a conical raceme, lower inflorescence branches curving.
- Leaves: Alternate, stalkless, dense. Blade narrowly elliptic, tapering base, sparsely sharp-toothed–almost with entire margins, upper side somewhat glabrous and glossy, underside short-haired.
- Fruit: Cylindrical achene with downy tip.
- Habitat: Yards, meadows, waste ground, railway embankments, roadsides, waterside. thickets. Also ornamental.
- Flowering time: August–October.
- Harmfulness: Harmful invasive species.
Only one native member of the goldenrod genus grows in Europe: goldenrod (S. virgaurea; also known as woundwort), which is common in Finland too. North America on the other hand has about a hundred species, which have evolved since it was taken across the Atlantic in the 17th century as an ornamental plant. Goldenrods from Canada and northern parts of the USA thrive in the similar climate of the Nordic countries and have become very popular in Finland in vegetable garden allotments and residential gardens. The first Finnish flower beds included Canada goldenrod, and it had already escaped by 1910. Nowadays it is often seen managing on its own in meadows and on banks, especially around areas that were previously cultivated. As a leftover from old gardens it can indicate an abandoned yard or garden, but usually it has struck out on its own. Because of its tendency to go wild Canada goldenrod should be classed as a nuisance, an alien species that poses a threat to our wildflowers.
When the spread of Canada goldenrod is contained and it is not allowed to escape, its positive qualities can be enjoyed in the garden. At its most handsome the species flowers from the end of summer until the winter: small golden yellow capitula adorn the plant in their thousands. The inflorescence lightens this large and luxuriant plant giving it a fragile quality – and some people also think that it looks messy. It does not always have time to flower properly in northern Finland before the winter sets in. Goldenrods are short-days plants: their flowering announces the season of lengthening nights and less daylight. The flowers attract a lot of insects, the most pleasing to people being colourful butterflies. The late flowering time provides an excellent source of nutrition for insects that are preparing for the winter. Canada goldenrod spreads well by seed, so it is best to cut the heads after they have flowered. Canada goldenrod is being increasingly replaced in the garden by the even more handsome garden goldenrod varieties which have been developed by crossing Canada goldenrod with other varieties. Of the American goldenrods that now grow wild in Finland, giant goldenrod (S. gigantea) bears the closest resemblance to Canada goldenrod, although, as the name suggests, it is bigger.