Journal archives for October 2017

October 13, 2017

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 on October 13, 2017 05:49 PM by nathantaylor nathantaylor | 5 comments | Leave a comment

October 18, 2017

California Euphorbs of subgenus Esula

The California Esulas are so much easier than Texas Esulas. The hardest part is that there are so many more observations to go through (in 2017: 1896[Euphorbia] - 1067[Anisophyllum] - 47[Alectoroctonum] - 19[Poinsettia] = 763[Esula]). It's best to start out learning the species in this key: In addition to that, 5 other species are found in CA: E. characias, E. cyparissias, E. exigua, E. serrata, E. amygdaloides, and E. segetalis based on FNA and the observations on iNaturalist. Some of these may only be present in cultivation, but the observations were not clear enough to tell. The characteristics are given below:

E. characias: only species with hairy fruits; dichasial bracts connate (fused together) halfway or more; somewhat similar to E. virgata but larger and has glands without horns or much smaller horns. Based on reviewed iNaturalist observations.
E. cyparissias: like E. virgata, but narrower leaves. Based on FNA.
E. exigua: annual with linear, entire leaves; imagine a linear-leafed E. peplus with acute apices. Based on FNA and reviewed iNaturalist observations.
E. serrata: like E. terracina but without horns on the glands and much deeper serrations on the leaves. Based on FNA; may be extirpated.
E. amygdaloides: like E. characias but with glabrous fruits; dichasial bracts obviously connate about half-way. Unconfirmed outside of cultivation but commonly planted and observed. Based on reviewed iNaturalist observations.
E. segetalis: like E. virgata but appearing stouter with thicker leaves, rougher fruits, and shallowly pitted seeds. Based on reviewed iNaturalist observations.

There are a few other commonly cultivated species that I need to learn just in case. Hopefully, I will get a chance to modify this into a more useful form and put it on the US Euphorbias project.

Other cultivated species:
E. epithymoides
E. lucida
E. x "Blue Haze"
E. mauritanica
E. × martini (E. amygdaloides x characias)

Posted on October 18, 2017 05:56 AM by nathantaylor nathantaylor | 2 comments | Leave a comment

October 20, 2017

SE Arizona perennial Tithymalloids

This is just so I can keep track of the different forms of the perennial Tithymalloids (subg. Esula) I saw on the SE AZ iNatathon earlier this year. One of the forms is quite odd and doesn't fit the descriptions of either E. brachycera or E. chamaesula very well.

Dichasial bracts elongated; mostly convergent horns: (Discussion) (Discussion)

Dichasial bracts less elongated; mostly divergent horns:

Posted on October 20, 2017 10:13 PM by nathantaylor nathantaylor | 5 comments | Leave a comment

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