Laudator Temporis Acti

One of the most persistent weeds in my yard is spotted spurge, Euphorbia maculata.

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The spotted of the common name means the same as the maculata of the scientific name. The Latin noun macula means spot or stain, and that which is immaculate is without spot or stain.

The Online Etymology Dictionary derives spurge

from O.Fr. espurge, from espurgier "to purge," from L. expurgare, from ex- "out" + purgare "to purge" (see purge). So called from the plant's purgative properties.

Besides the noun spurge, there is an obsolete verb spurge, defined by the Oxford English Dictionary as "To cleanse, purify (a person, the body, etc.); to free from or rid of impurity." One could therefore say of me, "He was spotted trying to spurge his yard of spotted spurge."

Euphorbia is an eponym, and we know the history of its coinage from Pliny, Natural History 25.38.77-78 (tr. John Bostock & H.T. Riley):

In the time, too, of our fathers, King Juba discovered a plant, to which he gave the name of "euphorbia," in honour of his physician, Euphorbus, the brother of the same Musa, whom we have mentioned as having saved the life of the late Emperor Augustus. It was these brothers who introduced the practice of douching the body with large quantities of cold water, immediately after the bath, for the purpose of bracing the system: whereas in former times, as we find stated in the works of Homer even, it was the practice to wash the body with warm water only.

With reference to euphorbia, there is a treatise still in existence, written upon it by King Juba, in which he highly extols its merits: he discovered it growing upon Mount Atlas, and describes it as resembling a thyrsus in appearance, and bearing leaves like those of the acanthus.

Invenit et patrum nostrorum aetate rex Iuba quam appellavit Euphorbeam medici sui nomine. frater is fuit Musae, a quo divum Augustum conservatum indicavimus. iidem fratres instituere a balineis frigida multa corpora adstringere; antea non erat mos nisi calida tantum lavari, sicut apud Homerum etiam invenimus.

sed Iubae volumen quoque extat de ea herba et clarum praeconium. invenit eam in monte Atlante, specie thyrsi, foliis acanthinis.

King Juba's treatise is lost, alas. There is supposed to be a similar story in Galen, De Compositione Medicamentorum Secundum Locos 9.4, which I haven't seen. The plant discovered by King Juba was not Euphorbia maculata, but probably Euphorbia officinarum.

Like most names, Euphorbus itself is more than just a collection of meaningless syllables. It is derived from the Greek adverb εὖ (eu = well) and the verb φέρβω (pherbō = feed, nourish). Therefore from an etymological point of view Euphorbus means well nourished, i.e. corpulent, fat.