Giant and Not So Giant Ragweed: September 2022

Ragweed pollen is a common allergen. A single plant may produce about a billion grains of pollen per season. Curiously, The genus name is from the Greek ambrosia, meaning “food or drink of immortality”.

We have two species commonly found in our area.

Giant Ragweed is a native species which is often found on river floodplains. It can grow up to 15 feet in height.

I found plenty of it during a walk along the Don River.

Giant Ragweed (Ambrosia trifida)
Giant Ragweed (Ambrosia trifida)
Giant Ragweed (Ambrosia trifida)

Common Ragweed is also considered native and is very weedy in habit. It can grow up to 6 feet in height.

Ragweed (Ambrosia artemisifolia)
Ragweed (Ambrosia artemisifolia)
Ragweed (Ambrosia artemisifolia)
Ragweed (Ambrosia artemisifolia)

Other plants by the Don River:

Pinkweed (Persicaria pensylvanicum)
Wild-cucumber (Echinocystis lobata)
Evening Primrose (Oenothera)
Soapwort (Saponaria officinalis)
Tansy (Tanecetum vulgare)
Soapwort (Saponaria officinalis)
Spearscale (Atriplex patula)
Calico Aster (Symphyotrichum lateriflorum)
Staghorn Sumac (Rhus typhina)
White Snakeroot (Ageratina altissima)
Canada Goldenrod (Solidago canadense)
Crown Vetch (Securigera varia)
Queen Anne’s-lace (Daucus carota)
Teasle (Dipsacus fullonum)

Area views:


Interesting speculations about these immigrants from the 1960s:



On roadsides, in fall fields,

in rumpy bunches,

saffron and orange and pale gold,

in little towers, soft as mash,

sneeze bringers and seed bearers,

full of bees and yellow beads

and perfect flowerlets

and orange butterflies. – Mary Oliver

Miles Hearn

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