Portraits of Wildflowers

Perspectives on Nature Photography

Horseweed

with 35 comments

Even though horseweed is one of the most widely distributed native plants in North America, it seldom if ever gets its praises sung. With that in mind, let me at least do some humming in favor of Conyza canadensis. Below you get a closer look at the seemingly energetic way the leaves on the main stalk dry out.

For temporal balance, have a look at those leaves on a fresh plant:

And here’s a closer look at a maturing inflorescence:

All these pictures come from the Blackland Prairie in northeast Austin on August 24th.

© 2019 Steven Schwartzman

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Written by Steve Schwartzman

September 12, 2019 at 4:08 AM

35 Responses

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  1. I’m so enjoying your appreciation of Texas wildflowers.

    lulu

    September 12, 2019 at 6:59 AM

    • Glad to hear it: that’s what this blog is here to promote. Texas has more native species than you can shake a stalk at, so to speak.

      Steve Schwartzman

      September 12, 2019 at 7:15 AM

  2. At first, I didn’t think I’d ever seen this plant, but when I looked at its early stage, I reconsidered. I am sure I’ve never seen it in bloom. It’s shown in my area, but not where I’ve been hanging out in the Big Thicket, so I need to abandon the woods, get back on the prairie, and look around. The way the leaves are intertwined with the buds in that last photo is wonderful.

    shoreacres

    September 12, 2019 at 7:41 AM

    • I’m pretty sure you’ve seen horseweed, even if it didn’t register. The species is quite common and its erect growth habit lifts it above many other plants around it—it literally stands out.

      When I scheduled this post a while back, the fourth picture wasn’t part of it. Just last night I looked once again at the photographs I took that day and realized the extra image would be a good addition. You’ve made me realize how interesting those intertwined leaves are.

      Steve Schwartzman

      September 12, 2019 at 8:05 AM

  3. Horseweed must be a plant that loves dry conditions. Here in the Kootenays, where we have plenty of rain except for the summer months, I have not seen this plant. Thanks for sharing this interesting bit on the horseweed, Steve!

    Peter Klopp

    September 12, 2019 at 8:18 AM

  4. I hope I never need to draw this plant…it looks complicated. I thought, like Peter, that it has a drylands look to it.

    melissabluefineart

    September 12, 2019 at 8:59 AM

    • Horseweed’s common occurrence in Texas might make you think of a dry environment, but check out the USDA map and you’ll see practically every county in Louisiana, Mississippi, and Florida have reported the plant. More germane for you, horseweed grows in every county in Illinois.

      I’ll take your word for the difficulties you might have in drawing horseweed.

      Steve Schwartzman

      September 12, 2019 at 9:26 AM

      • Yes, I thought it looked familiar but happily I think it is weedy enough I won’t need to draw it.

        melissabluefineart

        September 13, 2019 at 8:17 AM

        • Well, one person’s weed is another person’s wildflower.

          Steve Schwartzman

          September 13, 2019 at 8:55 AM

          • Yes, of course. Some of the highest quality species of butterfly, for example, are basically LBJ’s…Little Brown Jobs.

            melissabluefineart

            September 14, 2019 at 7:53 AM

            • What do you mean by “highest quality species”?

              Steve Schwartzman

              September 14, 2019 at 8:00 AM

              • Usually that means very rare, because they are tied closely to a high quality habitat. They can be indicator species. For example if a rare darter is present in a stream you know the water is very clean because they cannot tolerate any pollution or changes in temperature. Or they can be keystone species, whose extirpation causes a domino effect, a cascade of loss of other species. For example, salmon are dwindling drastically. As a result, bears, whales and sea lions are starving and forests are dying. The trees need the nourishment of the decaying salmon bodies. Of course it isn’t only that killing the bears and the whales and the forests, but that chain of connection is certainly a big part of it.
                If a species turns up everywhere, in all different settings, it is generally thought of as weedy. That is all I meant before.

                melissabluefineart

                September 14, 2019 at 8:27 AM

                • Thanks for your explanations. Another way to look at a weed, then, is a species versatile enough to make a go of it in many environments.

                  Steve Schwartzman

                  September 14, 2019 at 8:33 AM

                • Yes. A generalist, and it is the generalists that will keep life going as we increasingly wipe out the wild corners of the world. Soon they will be elevated in our estimation!

                  melissabluefineart

                  September 15, 2019 at 8:43 AM

                • With horseweed’s erect posture, it’s already elevated, though I’ve striven to make it even more so in people’s estimation.

                  Steve Schwartzman

                  September 15, 2019 at 9:40 AM

  5. And yet another intriguing lesson from the Botany College of the Steves. (TM)

    Michael Scandling

    September 12, 2019 at 11:01 AM

  6. The dried foliage in the second image is quite interesting and pleasing to my eye!

    denisebushphoto

    September 12, 2019 at 6:01 PM

    • I’m glad to hear the second image pleases your eye, too. The way the leaves twist and crinkle as they dry out has fascinated me for some time.

      Steve Schwartzman

      September 12, 2019 at 6:38 PM

  7. The flowers are numerous and must be a bee cafeteria.

    Steve Gingold

    September 13, 2019 at 1:50 AM

    • I expect they draw a lot more bees than people in general or even photographers in particular.

      Steve Schwartzman

      September 13, 2019 at 5:15 AM

  8. I rather like horseweed. It shows up and adds structure without taking up too much area. Great set of photos!

    Tina

    September 13, 2019 at 8:22 AM

    • Thanks. That’s a good observation: adding structure without taking up too much space. It’s why skyscrapers flourished in Manhattan.

      Steve Schwartzman

      September 13, 2019 at 8:57 AM

  9. Horseweed is called Mares Tail around these parts. For some reason it was very prolific this year on our orchard property. Thankfully, it has shallow roots and can be pulled up fairly easily. Deer and other mammals probably enjoy the cover it offers when a colony is formed. I have never seen anything eat on it, but I’ll wait and see if this winter that perhaps birds might utilize it somehow. One never knows the value of a “weed” until it’s had a full year’s cycle of seasons.

    Littlesundog

    September 14, 2019 at 9:45 AM

    • You got me wondering about the ways in which animals use horseweed. The Illinois Wildflowers website has a lot to say about that: “The flowerheads of Horseweed (Conyza canadensis) attract small Halictid bees, Sphecid wasps, Vespid wasps, Perilampid wasps, Syrphid flies, Tachinid flies, flesh flies (Sarcophaga spp.), Muscid flies, plant bugs (Miridae), and other insects. Bee visitors suck nectar or collect pollen, fly visitors suck nectar or feed on pollen, while the remaining floral visitors feed on nectar (Graenicher, 1909; Robertson, 1929). A variety of insects feed on the leaves, bore through the stems, or consume other parts of Horseweed. These species include the stem-boring larvae of a tumbling flower beetle (Mordellistena pustulata), larvae of Calycomyza humeralis (Aster Leafminer) and other leaf-miner flies, larvae of Asteromyia modesta (Horseweed Blister Midge) and Neolasioptera erigerontis (Horseweed Stem Gall Midge), Lygus lineolaris (Tarnished Plant Bug) and Taylorilygus apicalis (Broken-backed Bug), Uroleucon erigeronense and other aphids, Melanoplus differentialis (Differential Grasshopper) and Oecanthus quadripunctatus (Four-spotted Tree Cricket), and the larvae of such moths as Cucullia alfarata (Halloween Paint), Cucullia speyeri (Speyer’s Paint), Schinia arcigera (Arcigera Flower Moth), and Schinia lynx (Lynx Flower Moth); see Ford & Jackman (1996), Spencer & Steyskal (1986), Felt (1917), Snodgrass et al. (1984), Hottes & Frison (1931), Blackman & Eastop (2013), Joern (1985), Gangwere (1961), Wagner (2005), and Wagner et al. (2009). Mammalian herbivores usually leave Horseweed alone because the foliage is resinous and bitter (Georgia, 1913). However, deer and rabbits sometimes browse on young plants (Noble Foundation, 2007; personal observation), while to a minor extent muskrats eat the stems of plants that grow near bodies of water (Hamerstrom & Blake, 1939).”

      Now you have some ideas about what you might see on the horseweed plants on your property.

      Steve Schwartzman

      September 14, 2019 at 10:49 AM

      • This solves a mystery for me as to why I’ve been stung by wasps numerous times this summer (and have realized I have a localized allergy to them). I was always working in the blackberry thickets or my garden where lots of horseweed had popped up – which I happened to be eradicating!

        Thank you for posting the information you found. I have always said every plant has importance to the environment.

        Littlesundog

        September 14, 2019 at 12:47 PM

  10. That distribution map is impressive, Steve, but I can honestly say that I have never seen this plant, at least not consciously.

    tanjabrittonwriter

    September 14, 2019 at 8:00 PM

    • And I can honestly say that I’m not surprised. People consider this plant weedy and tend not to pay attention to it. You may have seen it without noticing, or maybe it’s not as common where you are and you really might never have come across it. Now that you’re aware of it, perhaps you’ll see it.

      Steve Schwartzman

      September 14, 2019 at 10:22 PM


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