Know thine enemy: Three-seeded mercury

Finally, I know who this fellow is, sort of. Acalypha…somebody, probably rhomboidea, commonly known as three-seeded mercury. He and his brothers are everywhere in my garden.

three-seeded mercury, Acalypha virginica

This annual member of the Euphorbiaceae family starts as a thin, erect reddish stem with narrow leaves, about an inch to an inch and a half long, arranged opposite along the stem. As it grows, it branches, and leaves are arranged alternately. Here is where my ignorance of botany is exposed:There appear to be small yellow flowers at the leaf axils, but those yellowish bits I see could be bracts, or technically it might be an inflorescence …anyway, if you care to read details about the plant’s structure, you can read the description from the University of Guelph extension, or the Wikipedia site. For me, right now, I know I’m fairly close to identifying the plant.

This summer annual weed is not a nuisance, except that there’s a lot of it in my garden. It doesn’t reseed aggressively like hairy bittercress and it’s not difficult to eradicate. Despite the taproot, the plants are easy to pull. They are also said to be browsed by deer (not if there are phlox and hosta to eat, they’re not).

three seeded mercury acalypha virginica

According to the Southern Living Garden Problem Solver, which may or may not have misclassified this as Acalypha virginica (my plant definitely doesn’t look like the one shown by Illinois, many insects love to feed on the leaves. Thus, my sample, with its raggedy, chewn leaves should be pretty typical.

The seeds are supposed to be choice food for mourning doves, whom I would gladly welcome to my garden because I love their call. The buffet is open!


Know thine enemy: Hairy bittercress

Continuing in my quest to learn my weeds, today I am studying hairy bittercress, Cardamine hirsuta.

This is a photo of hairy bittercress in its less aggressive form (yes, dead; but I meant in flower, before the seed pods form).

hairy bittercress

It is a winter or summer annual, depending on where you live. Perhaps in mild-climate areas, you are fortunate to have it all year round. The leaves appear in a tidy basal rosette, typically (for me) about 4 inches across. A single, neat, wirelike stem holds the tiny white flowers. Its innocent, almost dainty appearance may lull the gardener into deciding it can’t be that bothersome. Friend, be advised: Kill it immediately, and twice if you can.

Sometime in the course of the summer, hairy bittercress loses its innocence; its mate is obvious. Its seeds form in a silique (new Scrabble word!), which, of course, is Latin for “God-forsaken instrument of perpetual despair.” On an August afternoon, ambling through the garden on the way back from the mailbox, you may be tempted to do a light bit of weeding. You reach down for the spindly, twiggy wretch of a plant that you think, surely, must already have popped its clogs. You are just doing a bit of tidying. So at your gentle tug, you are shocked to hear a soft pop and witness a hailstorm of tiny seeds scattering in a circumference of astonishing size. You immediately enter the first of the five stages of grief: I didn’t just reseed this blasted waste of chlorophyll, did I?

Boy howdy, did you. Clearly, the way to deal with this plant is to search it out fearlessly and mercilessly in its youthful flower. Its fibrous root system makes it easy to extract, especially after a rain. But if, dear gardener, you go on vacation and allow circumstances to get to this burnt-twig phase, the plant is best extracted from the garden in the way good citizens dispatch dog poop:

  1. Ensleeve your arm with a plastic bag.
  2. Approach the target with the sensitivity of an explosive ordnance disposal tactician plying her craft.
  3. Pinch (or nearly pinch; now is not the time to detonate) the target (in this case, the stem) at its base.
  4. Invert the bag back over the target.
  5. Yank from the ground.
  6. Tie up tightly.

Whether further measures must be taken to ensure eradication (setting fire to the bag, collecting resulting ash and encasing it in a lead box, escorting lead box to Yucca Mountain, etc.) is a decision only the gardener can sort out by weighing his wallet and his conscience. The local fire brigade may have an opinion on the matter. Or, the gardener can wait until next spring (or winter, or maybe just late fall), when it will bloom again, providing another Sisyphean opportunity.


Know thine enemy: Learning about weeds

I listen to Margaret Roach‘s excellent podcast, A Way to Garden, and read her website of the same name. This year Margaret has been seeking to identify the weeds in her garden, to better understand their life cycles and ultimately get the upper hand on them.

This is wise advice, and I am hoping to (gradually) acquire this knowledge of the plants in my own garden with which I wage perpetual battle. Today I am starting with an easy one: spotted spurge, known also as Euphorbia maculata or Chamaesyce maculata.

spotted spurge, photo courtesy wikipedia

Although it grows from a taproot, I have always found spotted spurge fairly easy to pull up with a hand rake. But maybe this is my problem: Perhaps my technique yields the topgrowth, but part of the taproot remains, leaving a source from which it can regrow. Or my problem could be that I have a lot of it and don’t get around to eradicating it, so it multiplies.

This is a summer annual weed, which means that if I can get to it early (and get that taproot!), before it sets seed, I should be able to get it under control. It emerges in mid-summer, and can flower within 3 to 4 weeks according to NC Turffiles, so that time before flowering is the critical window in which I need to act. I fear the ship may have sailed, but I may still be able to row after it. Summer lasts a long time where I live.

Also, like many Euphorbias, its stems contain a sap that can be irritating to sensitive skin. Must remember to get out the gloves.

If you have spotted spurge in your lawn, you can help control it by raising the cutting height of your lawn mower. Higher-standing grass cuts down on the amount of light reaching the weed seeds in the soil. As it happens, I don’t have a lawn to mow. But I do have plenty of spots that could use a good top-up with mulch, which is also an effective control.