Portraits of Wildflowers

Perspectives on Nature Photography

A family resemblance

with 7 comments

A giant ragweed stalk with a sunflower behind it; click for greater detail.

Now that you’ve gotten a close look at the tiny flowers of giant ragweed, Ambrosia trifida, the only thing you might think they have in common with a sunflower is the bit of yellow at the lower end of each “bell.” Yet botanists have placed ragweeds in the same family as sunflowers, the huge composite family known technically as the Asteraceae, which includes asters, daisies, thistles, and a lot more. Although the wind-pollinated flowers of giant ragweed and the insect-pollinated flowers of the familiar sunflower (one of which you see here out of focus in the background) are so unlike, the plants themselves have some similar features: both often grow taller than a person, and both are stocky and coarse and covered with rough hairs. Look at the giant ragweed stalk in today’s photograph, taken back on June 22, and compare it to the stalks of mature sunflower plants you’ve seen, or to the one shown in this column on June 23. Look also at the young ragweed leaf in the upper right of today’s picture and compare it to the young sunflower leaves featured in the first days of this blog. Welcome to the family.

I made this photograph, like a number of the others that have appeared in this blog, in Austin on the lot on the east side of US 183 south of Braker Lane that’s adjacent to Costco and Wendy’s. That property is in the midst of being redeveloped, so I don’t know how much longer I’ll be able to go photographing there.

For more information about Ambrosia trifida, including a clickable map showing the great many places in North America where the plant grows, you can visit the USDA website.

© 2011 Steven Schwartzman

Written by Steve Schwartzman

September 17, 2011 at 6:00 AM

7 Responses

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  1. I only realized a year or so ago how big the sunflower family is and I was amazed.

    Candace

    September 17, 2011 at 5:02 PM

    • Yes, it’s enormous. It’s the botanical family with the greatest representation in central Texas.

      Steve Schwartzman

      September 17, 2011 at 6:04 PM

  2. […] picture of a giant ragweed stalk near a sunflower comes from the afternoon of June 22. That morning I’d made a visit to the same site and had […]

  3. […] give way to the growing greens of this one. So it is with giant ragweed, Ambrosia trifida, whose sturdy new stalk and upside-down flowers that push pollen out into the air long-time visitors to this column have […]

  4. […] A family resemblance […]

  5. […] One of the treats of autumn is goldenrod (genus Solidago), a flowering cohort of which you see here. The tall, dried-out stalks are from the previous year’s colony of giant ragweed, Ambrosia trifida. […]


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