Stolons emerge from stem nodes which contain growth cells that adapt to become roots as they touch the soil. When nodes on stems touch ground and form stolons, or new roots, new cloned plants emerge from these roots to spread the original parent plant into a colony of separate new plants, all interconnected and marking territory.
Stem nodes are the points along the stem from which leaves, branching stems, flowers, roots, tendrils and other growth parts emerge. Plant growth takes place in regions where cells actively divide. These growth or “meristematic” cells go through division and rest stages, “mitosis” and “interphase”, to multiply and reproduce themselves. As cells mature they change shape to suit the cell’s ultimate function, as root, stem, flower, or leaf. Growth cells at stem nodes adapt quickly to meet the changing requirements of the plants they form.
Other growth cells
Some other meristematic cells occur in roots and stem tips. Root cells help plants anchor themselves and absorb nutrients in the soil, stem tips help plants grow tall and help leaves, flowers, and tendrils to emerge.
Once the various roots of Ground ivy take hold, these stealthy weeds steal territory, linger from season to season, require little to keep nourished, creep into unnoticeable nooks and crannies, regenerate from broken pieces, and resist control. Ground ivy can destroy a lawn so completely that it may take a year of work to return the lawn to Grass. Ground ivy prefers to grow in a weakened lawn where it meets with less competition. It flourishes in shady lawns, especially in those tough spots that cultivated Grass avoids, such as under Oaks and Maples or in moist, undernourished, airless soil. It proliferates in soils low on the humus, potash and phosphates which all well-bred Grasses insist upon for survival. Some folks choose to let their lawns go to Ground ivy because they prefer its blue flowers in spring to plain old high-maintenance Grass. These more laissez-faire gardeners don’t even need to fertilize or aerate to keep these blue-flowered beauties alive.
Purple deadnettle, Lamium purpureum, also a ground covering Mint family invader, steals territory to form large colonies, especially in well-fertilized, well-watered lawns and gardens as well as in tough sites. It grows better in the ground that we disturb or cultivate than it does in the wild. In the fall and winter its offspring self-fertilize, build a storehouse of seeds, and gain strength to produce both new plants and profuse blooms from April to June. As if that isn’t enough, as the weather warms up, the abundant nectar of its summer blooms attracts bees and other critters to pollinate blooms to increase its seed production. A single plant, reproducing with this one-two punch, may generate over 27,000 seeds. It continues to bloom intermittently through October creating multiple generations. Dormant seeds remain viable for 5-14 years, just waiting to awaken. Like Ground ivy it spreads unnoticed as its prostrate stems form “stolons”, or roots wherever stem nodes touch ground to create more plants. Nothing is lame or dead about this nettlesome purple perennial invader.
Like its Minty cousins, Heal-all, Prunella vulgaris, grows in rich, fertile, moist soil, but gains its greatest competitive advantage in soil low in calcium, humus and air, since it processes nutrients using anaerobic bacteria common to wet compacted soil.
My first season, I found Heal-all in bloom by the side of the front path closest to the house. Not sure of its identity, I asked a few contractors, my arborist, and my local nursery people and they all said, “I have it and I believe it’s a weed, but I’m not sure”. Finally, I saw it for sale (!!!) at a nursery. I guess it was some presumably less vigorous hybrid, or at least I hope so. Armed with a name, I found it featured as a weed in several, but not all, source books. Sadder, but wiser, I pulled it out, but found it yet again the following year, this time on the other side of the path. It seemed as if the roots had crawled under a three-foot wide asphalt path. Perhaps it had sown its seeds across the way. Bottom line, it spread and killed off the Grass nearby. After a long winter, Heal-all’s profuse purplish-blue blooms temporarily provided a welcome addition. I pulled it out, still reluctantly, since I was new to gardening, and had few blooms then. But I also wanted a smooth lawn. Heal-all lingered and continued to flower through November when it continued to shoulder Grass aside. It also began to creep, deceptively at first, into beds among my newly planted annual Pansies. As it mimicked the low sprawling habit and neat mounds of the Pansies, it hid in plain sight. The Pansies and other nearby tender seedlings lost the battle to this tough competitor. Even in the LIHRC (Long Island Horticultural Research Center of Cornell in Riverhead, NY ) weed garden, a garden filled with vigorous perennial weeds in pots, it stands out as a prodigious spreader that leaps out of its pot to grow most anywhere.
Fortunately most of these Mints make a beneficial tea and most have medicinal uses, especially as astringents. For example, Heal-all provides an effective styptic to staunch bleeding. Heal-all also helped heal “quinsy”, a type of sore throat that afflicted German soldiers in the battlefields in the 1600s. But the very name “heal-all” is quite misleading. It certainly won’t heal your daunted spirit as your tender seedlings lose their very first battle to its rapacious methods.
Left: Purple Deadnettle mat in lawn Right: Heal-all mat in lawn