The spots of Spotted Spurge (Euphorbia maculata)

About Fall time is when the "spots" in Spotted Spurge (E. maculata) start to disappear. Since "spotted" is actually in the name, there are typically a lot of misidentifications during this time of year. Euphorbia maculata isn't the only species that loses its "spot" at this time of year. Any species that has produced one will lose it during the fall as plants start to shut down. This also happens when plants are in too much shade and become etiolated.

This is also a good time to discuss the reliability of the spot in general. Ultimately, it cannot be relied upon for identification of a species. The presence or absence of the spot is completely variable and I have seen countless E. maculata plants without spots for seemingly no environmental reason whatsoever. However, the presence of a spot can be useful for excluding other species. Most species in the United States do not appear to have the ability to produce the spot (e.g., E. prostrata).

For more information on how to identify the species (including how it differs from E. prostrata) read here and possibly compare with some of the other species in The Weedy Species of Sandmats (Euphorbia sect. Anisophyllum) in Texas. I have not put together a guide for the common weedy species for the entire US, but the Texas guide covers all the major weedy species found throughout the US except in Arizona, New Mexico, Florida, and possibly California.

Posted by nathantaylor nathantaylor, October 13, 2017 17:49

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To any who read this, please spread the word! This has been posted 8 times this month (Sep 2018) after the observer expressed concerns over there being no spots on the leaves. This is fewer than last year, but since spotted spurge is so common, the amount of differing identifications based on the misunderstanding of this one characteristic can add up.

Posted by nathantaylor about 1 year ago (Flag)
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Thanks for the information

Posted by pattyseitz about 1 year ago (Flag)
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This is very informative.

Posted by bryn_potter 11 months ago (Flag)
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I agree, this is very informative. The E. maculata plants I encountered recently in southwest Turkey, during summer, not fall, appeared quite fresh and I don't think their leaves had ever had any spots. I will keep looking to see if I can find any specimens in the area that do have spotted leaves. It may be that spotless E. maculata is the norm here.

Posted by trcarlisle 3 months ago (Flag)
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It's not unusual to see spotless forms at any time of the year. Also, there are populations in the US that seem to routinely lack spots and it's possible that the plants in Turkey don't produce them as well. The character itself is quite unreliable except when used in the way specified above. The time of year is included here as that's the time when I usually get the greatest influx of comments asking about the spots (as most or all individuals lose their spots in the fall).

Posted by nathantaylor 3 months ago (Flag)

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