Portraits of Wildflowers

Perspectives on Nature Photography

From snow to fire

with 24 comments

Yesterday’s post showed you a happy colony of snow-on-the-prairie, Euphorbia bicolor. Now here’s one of its genus-mates, Euphorbia cyathophora, known as fire-on-the-mountain for the bright red of its bracts. Another common name is wild poinsettia, a reference to a more-familiar genus-mate, Euphorbia pulcherrima, that people decorate their places with during the Christmas season.

I photographed this fire-on-the-mountain on the morning of September 11th at the Lady Bird Johnson Wildflower Center. It hadn’t rained, but the staff waters the plants in the central courtyard, and that accounted for the droplets in the photograph.

♡     ♡
♡     ♡     ♡
♡     ♡

I’m reading mathematician Jordan Ellenberg’s new book Shape. Here’s a passage from the first chapter.

We encounter non-proofs in proofy clothing all the time, and unless we’ve made ourselves especially attentive, they often get by our defenses. There are tells you can look for. In math, when an author starts a sentence with “Clearly,” what they are really saying is “This seems clear to me and I probably should have checked it, but I got a little confused, so I settled for just asserting that it was clear.” The newspaper pundit’s analogue is the sentence starting “Surely, we can all agree.” Whenever you see this, you should at all costs not be sure that all agree on what follows. You are being asked to treat something as an axiom*, and if there’s one thing we can learn from the history of geometry, it’s that you shouldn’t admit a new axiom into your book until it really proves its worth.

Always be skeptical when someone tells you they’re “just being logical.” If they are talking about an economic policy or a culture figure whose behavior they deplore or a relationship concession they want you to make, and not a congruence of triangles, they are not “just being logical,” because they’re operating in a context where logical deduction—if it applies at all—can’t be untangled from everything else. They want you to mistake an assertively expressed chain of opinions as the proof of a theorem. But once you’ve experienced the sharp click of an honest-to-goodness proof, you’ll never fall for this again. Tell your “logical “opponent to go square a circle.**

A big reason we surely can’t all agree is that people often use a given term to mean different things. What one person considers a “fair share,” another person takes to be a disproportionate burden. One person uses “justice” to mean a desired outcome, while for another person “justice” means due process and equal treatment. If we don’t start from the same definitions, why would we expect to reach the same conclusions?

— — — —

* An axiom is a principle that everyone will take to be true and will use as a starting point to figure out other facts or relationships. For example, one axiom of mathematics is that a whole thing is equal to the sum of its parts. Another axiom is that two things that are each equal to a third thing are equal to each other.

** “Squaring the circle” was a geometric challenge that meant: Using only a compass, a straightedge, and a finite number of steps, construct a square that has the same area as a given circle. For centuries mathematicians tried and failed to figure out how to do that. In 1882, Ferdinand von Lindemann finally proved that squaring the circle is impossible. (So much for the common notion that “You can’t prove a negative. Sometimes you can.)

© 2021 Steven Schwartzman

Written by Steve Schwartzman

September 19, 2021 at 4:33 AM

24 Responses

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  1. Love the bold image – looks like it could just burst into flames!

    Ann Mackay

    September 19, 2021 at 6:43 AM

    • If it was about to burst into flames while I was photographing it, it gave me no warning. Still, I escaped unscathed.

      Steve Schwartzman

      September 19, 2021 at 8:17 AM

  2. I’ve never heard this plant called ‘fire on the mountain.’ I’ve only known ‘wild poinsettia.’ That said, I was introduced to it in Liberia, where it was plentiful, and I saw it again in the Canary Islands. I don’t know, but suspect, that the species there was E. pulcherrima. In any event, it looked just like the second photo in this article. The article notes that “It is a scraggly shrub that lives in seasonally dry tropical forests,” and that sure enough describes the Liberian bush.


    September 19, 2021 at 6:45 AM

    • One thing I learned from your linked article is that “all cultivated poinsettias have been purposely infected with a bacteria that stunts their growth, keeping them small and compact.” It does seem likely that the plants you encountered in the Canary Islands and Liberia were Euphorbia pulcherrima, whose species name is Latin for ‘most beautiful’—as opposed to the pretty but smaller and less striking wild poinsettia of Texas.

      Steve Schwartzman

      September 19, 2021 at 8:15 AM

  3. Many years ago I had a neighbor who was a ranch woman who had moved to town after her husband passed away, and with her she moved many native plants from the farm. She gave me seeds to what she called “wild poinsetta” and warned me how prolific they could be and to be careful where I planted them. She stated the seeds would burst from the pod and spread out several feet. Was she ever correct! I love the detail of your image, and that pop of red is what I’ve always loved about this plant. I see it here occasionally but mostly down in the wetland area of the property, specifically the old river channel.


    September 19, 2021 at 7:05 AM

    • I appreciate the information you’ve provided, which is new to me, mostly because I’m not a gardener. I don’t often encounter wild poinsettia when I’m out wandering, so I don’t have a feel for its growth habits. If you find a good stand down by your old river channel, maybe you can feature it in one of your posts.

      Steve Schwartzman

      September 19, 2021 at 8:27 AM

  4. I love those droplets and the light in them!


    September 19, 2021 at 8:54 AM

  5. Snow on the mountain is Euphorbia marginata. E. bicolor is snow on the prairie. In Central Texas E. marginata is the common one.

    Judy T

    September 19, 2021 at 8:57 AM

    • Thanks for catching my thinko. The picture I’d shown in the previous post was snow-on-the-prairie but I accidentally wrote snow-on-the-mountain. I’ve corrected the mistake. My mnemonic for keeping the two species names matched up properly is mountain and marginata both begin with m. Austin acts as an approximate divider of the two species, with snow-on-the-mountain generally on the west side of town and snow-on-the-prairie predominating in the east.

      Steve Schwartzman

      September 19, 2021 at 11:22 AM

  6. The fiery red decorated by these jewel-like dewdrops is truly impressive, Steve.

    Peter Klopp

    September 19, 2021 at 9:31 AM

  7. “If we don’t start from the same definitions, why would we expect to reach the same conclusions?”…

    ….another is calling us to simply ‘use our common sense’, when every individual grows up having his/her own take on what that is; and therefore not at all universal/common.


    September 19, 2021 at 1:18 PM

    • Ah yes, the [in]famous “common sense.” As you said, people differ a lot on what makes sense to them—and even when two people agree, they can both be wrong. This spring I wrote a bunch of commentaries, each of which showed that a commonly held notion is false. I think the last of them was:

      Texas flax

      Steve Schwartzman

      September 19, 2021 at 1:35 PM

  8. Water droplets no matter what the source are always a welcome addition. Of course the dark background sets them off very well as well.

    Steve Gingold

    September 19, 2021 at 3:56 PM

    • You know me with my dark backgrounds this past year. And yes, water droplets are natural attractants.

      Steve Schwartzman

      September 19, 2021 at 5:38 PM

  9. Very pretty flower photograph. I like the colors, contrast and how perfect the drops are The black background really helps the red to stand up.

    Alessandra Chaves

    September 19, 2021 at 8:31 PM

    • The background wasn’t completely black in a few places, so I darkened those to create uniformity and eliminate distractions.

      Steve Schwartzman

      September 20, 2021 at 3:49 AM

  10. […] our September 11th visit to the Lady Bird Johnson Wildflower Center produced pictures not only of a bright red fire-on-the-mountain bract but also of what I take to be a male neon skimmer dragonfly, Libellula crocipennis. This one was up […]

  11. Great shot Steve .. gorgeous red


    September 27, 2021 at 1:23 PM

  12. […] already seen Euphorbia bicolor, Euphorbia marginata, and Euphorbia cyathophora here this season. Now comes Euphorbia corollata, which doesn’t grow in Austin or anywhere […]

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