Monday, July 11, 2011


-            Anal compulsive that I am, I check statistics on this blog twice a day. Readers endlessly surprise me with which posts top the hits list. Through February, “Stuffing Stockings” (Dec. 10, 2010) far surpassed all the others. Lately, however, stockings have been left in the dust of “Winter Weeds” (Jan. 4, 2011) and the “Am I Blue Bonus” pictorial (Apr. 15, 2011), reinforcing my gut intuition that, when it comes to gardening matters, people want pictures—especially photographs—more than anything else.

            (I tried to explain this to Tom Fischer, editor-in-chief at Timber Press, when pitching my excellent but spurned Best Gardening Book Ever to him. His reaction to the revelation that I had in excess of 600 photos to illustrate the text was that pictures are expensive to reproduce. My reply that a gardening book without them is pretty well useless met with stony silence. Line drawings are lovely, of course—and cheaper to mass-produce—but don’t do the job as well as photographs. The rejection form-letter arrived several weeks later.)

            Publishing woes aside, the popularity of “Winter Weeds” speaks to a dire need that remains unmet for the gardening public: good pictorial references to common weeds. Which brings us, at last, to today’s subject.

            Summer weeds are more numerous than winter ones, which should come as no big surprise. There is also the whole when-is-a-weed-a-wildflower grey area to consider. So we’ll take up the subject in two, maybe three, maybe four, parts, starting with broadleaf annuals that are definitely weeds.
Spotted spurge
This ubiquitous fellow I call “the spurge of my existence.” His proper name is Euphorbia maculata, or spotted spurge. He can flower and produce seed in about five weeks, meaning he and every other member of his clan account for multiple generations each season. Prostrate and mat-forming in habit, spotted spurge has a taproot, explaining its infuriating ability to survive droughty conditions. He has many, equally prolific cousins, including garden spurge, hyssop spurge and sand-dune spurge. Find the center of the beast and pull straight up: it’s the only hope of removing this muggy-weather breeder taproot and all.

            Here is Phyllanthus urinaria, a.k.a. chamberbitter. One of two mimosa imitators, it is immediately identifiable later in the season when it sets seed. They’re the little greenish-yellow balls hanging beneath each pair of leaflets. Don’t bother looking for the flowers from whence the seeds emerge: they’re so inconspicuous as to be invisible.


Florida pusley
              Another common lawn invader is Florida pusley (Richardia scabra). An attractive weed with thickish bright green ovate leaves, it produces tiny, six-petalled, darlin’ white flowers later in the summer. Its habit is prostrate and spreading. But beware the ugliness behind the beauty: it reproduces rampantly by seed.

            This one, Diodia teres, is called poorjoe, and no, I don’t know why. I tend to confuse it with the similar-looking carpetweed, Mollugo verticillata, because both have prostate, spreading habits, reddish stems, whorled-looking leaves, and cute little white flowers. Poorjoe blooms have four petals, carpetweed’s have five. When you see flowers, regardless of number of petals, it’s time to yank it out of the ground, no matter what its name is.

Hemp sesbania
  The second of the two mimosa imitators, hemp sesbania (Sesbania exaltata) also shares the touch-me-not characteristic of sensitive plant. Although spuriously similar to chamberbitter, upon closer inspection you will discover that sesbania leaflets are finer-textured and a darker green. Sesbania blooms are a sunny yellow and reminiscent of pea flowers. They form in the leaf axils (where the leaf joins the stalk).

            Moving right along, check out these three perennial rhizomatous nightmares.

Pennywort, or dollarweed
            First is pennywort, or dollarweed, as the upscale call it (not really), the evil genus (pardon the pun) Hydrocotyle (that’s pronounced hi-dro-COT-ih-lee). I’m sure you’ll be thrilled to hear there are several species of this attractive but insidiously thuggish spreader. The one slowly taking over your planting beds and lawn is H. bonariensis; but as you may have surmised from the “hydro” part of the botanical name, there’s a water pennywort as well. When asked about controlling large infestations of this one, Tim and I generally advise clients to learn to love it. The alternative is to get your hands dirty and pull out some of those miles of white runners crisscrossing your property, because pennywort is notoriously chemical-proof.
Florida betony
          Next up in our gallery of difficult-if-not-impossible-to-eradicate thugs is Florida betony. Believe it or not, this dainty-looking little monster shares a genus name with silvery lamb’s-ears: betony is Stachys floridana, soft and fuzzy lamb’s-ear S. byzantina. Betony also goes by several other common names, including rattlesnake weed and false artichoke. The rattlesnake bit comes from the appearance of the tubers that ensure the immortality of this weed: the artichoke reference obscurely refers to the tubers, too. They are edible—meaning it won’t hurt you to eat them—but I can testify that they don’t taste like anything at all. Certainly not like any artichoke I’ve ever enjoyed. The tubers are connected by white rhizomes depressingly like pennyworts’, in behavior and quantity.
            Third is the Harry Potter-ish-sounding mugwort, Artemisia vulgaris. An interesting case of adaptation in the botanical world, mugwort doesn’t flower or set seed. It reproduces itself entirely by rhizomes. It looks sort of like chrysanthemum foliage, and is not unattractive. But my weed-ID guy at Virginia Tech, Scott Hagood, says mugwort has definite aggression issues, aggravated by being difficult to eradicate.

            Two other see-everywhere perennial weeds will wrap up today’s post, because it’s almost time for “Jeopardy!” 
Yellow woodsorrel

Creeping woodsorrel

            Many people consider members of the genus Oxalis to be ornamental… and I can’t say I entirely disagree. The neat foliage, reminiscent of clover, and the pink flowers of the species everyone’s mom and grandma grew when I was a kid evoke summer memories, hot pavement under bare feet and the mingled smells of road tar and cut grass. But when Oxalis edges over into its woodsorrel incarnation, the charm rapidly dissipates. Here on the eastern coast, we see two species: Oxalis stricta, or yellow woodsorrel; and O. corniculata, creeping woodsorrel. The yellow variety is upright, with light green foliage. The creeping type is prostrate: its leaves can be green or red, and it spreads (and spreads and spreads) by rooting from nodes on its lax stems. Both are prolific seeders, so try to catch them while they’re blooming. Because once the seed capsules form, it’s too late.

             I’m of two minds about bindweed (Convolvulus arvensis). On the one hand, it’s pretty in foliage and flower, as one would expect from a morning-glory relative. On the other hand, its wiry stems expand at about a mile a minute, and its capacity to smother and strangle other plants is impressive. So how do I handle bindweed outbreaks chez Fitzgerald? If I spot its distinctive cotyledons, or seed leaves, anywhere in the yard, I root them out right away. But if it shows up in other places, draping a scrub tree in the vacant lot next door, say, I’m completely okay with that.

            As I mentioned back at the beginning, there are lots more summer weeds than winter ones. Next time, we’ll continue our tour through the perennials and move into the grass-like species. See you then.

            A quick astronomical note: tomorrow, July 12th, the planet Neptune completes its first orbit around the sun since it was discovered by German sky-watchers Galle and d’Arrest back in 1846. They were clued in about where to look by calculations made by French mathematician Le Verrier, who couldn’t interest anyone in his own country to take him seriously. Those wacky French!

            Thanks for dropping by.