Goldenrods are in the Solidago family. In Latin, Solidago means to make whole and refers to some healing capabilities of the plant.
They carry a bad reputation as being a cause of hay fever which afflicts many people in September. This is because the plant is very visible and found all over in September. In fact, hay fever is caused largely by Ragweed which is less noticeable but very present in urban areas.
There are many kinds of Goldenrod but the ones we see most frequently in the Toronto region share an identifying characteristic. The leafs have 2 prominent veins parallel to the midrib as you can see in this photo.
This narrows the identification down to 3 species: Late Goldenrod, Canada Goldenrod and Tall Goldenrod.
To tell Canada and Tall Goldenrod apart you must measure a tiny part of the flower. If it is over 3 mm long it is Tall Goldenrod. Under 3 mm and it is Canada Goldenrod.
Here are the leaves of one of these.
In addition the stem of both species is somewhat rough, definitely not smooth.
Goldenrods are Composite flowers meaning that the flowers contain 100’s of individual small flowers.
Late Goldenrod resembles Canada and Tall Goldenrod and can easily be mistaken for one of them.
Despite the name “late”, I found many in flower at the end of July at Scarborough Bluffs.
“gigantea” mean “gigantic” and comes from the height of the plant which is can be over 2 meters.
The easiest way to distinguish Late Goldenrod from Canada or Tall Goldenrod is by close examination of the stem. The stem of Late Goldenrod is noticeably smooth.
It almost looks shiny.
To add confusion to the Goldenrod family, a common plant called Lance-leaved or Grass-leaved Goldenrod is no longer considered by scientists to be part of the Goldenrod family.
It is now part of the Euthamia family. Euthamia is Greek for well-crowded in reference to the many, many flowers.
Here you can see the lance or grass-like leaves.
Graminifolia means that the leaves look like grass.
The plant has a flat-looking top unlike the pyramid look of many goldenrods.
Here is a close-up of the flowers.