Question 6

Does it grow where nothing like it was planted?

As mentioned in Q#1, in a “mono-culture”, a bed where only one crop grows, for example, only Corn, and where there are wide unplanted rows between crops, weeds stand out. If you plant only Roses, or only red Tulips, or only Daylilies, weeds stand out. These well-organized plantings highlight anything that is OTHER that sprouts up, the same way rock mulch highlights anything green that sprouts up.

In a mixed planting, the process of recognizing weeds becomes more complex. You can spot broad-leaf plants growing amidst the Grasses as being out of place, or Grasses growing in your flower borders that look nothing like the broad-leaf flowers you planted. But even these parameters fail to clarify just what plants are weedy.

EXCEPT

You may just have forgotten what you planted. Get to know the plants you’ve chosen so you can better recognize those that you have not chosen. This will help you make an informed decision.

Low-growing Volunteers

I first spotted Spurge in a hot spot in my flower bed where a few drought loving cultivars and weeds were growing. I know I hadn’t planted any groundcover there, except some Sedum and it sure wasn’t Sedum. I found it again as it grew between the bricks in a walkway. I knew, once it showed itself in that sun-baked, infertile, spot that it was most likely a weed. I just needed to find its name—“spurge”.

Left: Prostrate spurge (roots pulled) volunteers in a sunny bed Right: Spotted spurge flourishes in walkway crack

Spotted and prostrate spurge, Chamaesyce maculata and prostrata, respectively, give me the urge to purge them as a scourge. Debate continues about the differences among the sub-species and their Latin binomials—but in general, maculata have spots and don’t have stolons, prostrata don’t have spots but do have stolons. Whatever you choose to call them, these two low growers are weedy and problematic. Most lawn care providers consider either one “noxious”, since both flourish below mower cuts. Much like Crabgrass, they take root in the type of dry, compacted, or airless soil that causes turfgrass to struggle too much for survival. Once established, they easily out-compete the now-daunted grasses. They invade pathways, driveways, and barren roadsides, to flourish in tiny cracks and thin sand. The same organic methods that thwart the non-toxic invader, Crabgrass, covered in Q#1 under: “Tips to Control Crabgrass and Dandelion”, work somewhat to thwart or at least slow the spread of Spotted or Prostrate spurge. All of these will still spread into fertile garden beds too, alas, but you can diminish their numbers.

Both spurges belong to the often toxic Spurge, Euphorbiaceae, family, which also includes choice specimens like mildy toxic Poinsettias and highly poisonous, but vividly ornamental Castor bean, Ricinus communis. Features they share with others in the Euphorbia family include: a milky—potentially poisonous—juice within plant parts, tiny flower groupings in a small cup called a “cyathium”, and a profusion of three-part fruits that encapsulate 3 seeds. Features they share with others in its smaller genus Chamaesyce include the above plus special photosynthetic abilities (C-4 see Q#1) which help it compete well in drought, succulent stems and leaves that also conserve water, plus low sprawling growth. As with many toxic plants, folk pharmacopeias claimed them as medicine: diuretic in very small dose, emetic and purgative in larger doses, capable of shrinking warts, branding cattle, and poisoning rodents. Scientists continue to test the effects of some of their steroids, such as diterpene ester. Somehow, a toxin that brands cattle sounds to me like an unpredictable and even unwholesome medicine.