A page from my journal showing drawings of buckthorn.
Here's a factoid in the category of "Who knew?" The original base for the color Sap Green is the buckthorn berry! This strange fact appeared in one of color-expert Michael Wilcox's books, The Artist's Guide to Selecting Colors.
Somehow this struck me as a rather amusing anecdote. I learned as a young watercolor painter that Sap Green was a color that was well avoided because it was fugitive. For you non-painters that means the color you painted will fade away if not disappear. Early in one's painting life the tendency is to collect lots of colors premixed in tubes in the hopes that having just the right supplies (preferably lots of them) will result in wonderful paintings. Sap Green is out there giving the siren call along with myriad other colors. Alas, it is "brush time" that gets you the results you are after. But that is a discussion for another day.
So, what is amusing about Sap Green coming from the buckthorn berry? It is because the buckthorn bush will not go away! Anyone who knows anything about buckthorn would wish it to be fugitive. Such irony.
Imported as an ornamental plant, often sold for use as hedge material, the buckthorn has become a full fledged invasive pest. The stuff is everywhere. The drawing above was done this morning right off my deck. Years of mowing, pulling, and poisoning have not kept it from our property. I have watched the beautiful oak savannah across the street from our house be invaded by buckthorn in the 25 years we have lived here. The stuff is nasty--it even has thorns. Worse, it is among the first to green up and the last to loose its leaves so you see it as a low (1 to 6 foot) green haze in the spring and fall. www.dnr.state.mn.us/invasives/terrestrialplants/woddy/buckthorn/index.html
According to Wilcox, Sap Green was originally made without a binder. The juice was sticky enough on its own. After it thickened it was kept in an animal bladder ready for the lucky painter. Wilcox notes that there are a few Sap Greens that are now more permanent, however he says it is, "usually a disastrous substance well worth avoiding. Such dull greens can easily be mixed from Ultramarine Blue and Cadmium Yellow Light, perhaps with a touch of violet-red." (p. 82)
I agree. Mix your own dull olive Sap Green color. And get rid of your buckthorn hedge if you have one.