Flower of the Day: Giant Ragweed

Ambrosia trifida; Asteraceae (aster family)

20140818-DSC_0094

After posting about goldenrods over the last few days, I have to take this opportunity to dispel a common myth: goldenrod pollen is not an allergen.  The culprit at this time of year is ragweed.  Goldenrod takes the blame because it’s so showy, but ragweed, with its tiny little unassuming flowers, is doing the damage.

Actually the flowers are quite interesting.  They are completely without petals or sepals.  Each of the yellow dots in the picture above is an individual flower.

There are three species of ragweed found in this area.  The one pictured here can grow to 12 feet tall, and is found in every state of the union except Nevada. Here’s a leaf, which can get to a foot long:

20140818-DSC_0089

The other species are annual ragweed (A. artemisiifolia, with three subspecies, one alien and two native), and Cuman or perennial ragweed (A. psilostachya). The former is found everywhere; the latter everywhere except Delaware, Maryland, Virginia, West Virginia, and Kentucky.

All of these ragweeds are listed as weedy and/or invasive by multiple authorities.

Remember: don’t blame the goldenrods for your misery.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s