Smartweed is one of those plants that blurs the line between weed and garden plant
I paused my shoveling of horse manure the other day to rest my eyes on a most attractive plant growing at the edge of the pile.
This semi-vining plant had swollen, slightly reddish joints — almost like knees — to which were clasped lush, lance-shaped leaves. Individually, the flowers were small, each a round knot about the size of a millet grain, but they clustered together along the last couple of inches of each stem like colorful droplets.
I quickly reminded myself that the object of my admiration was a weed: smartweed. Once again, that line dividing weeds from garden plants blurred.
No, I'm not about to transplant smartweed to my garden. I do realize that much of its attraction was finding beauty where it was unexpected.
Smartweed (also known as knotweed) is the common name given to a whole genus of plants, Polygonum, which translates as "many knees." Many members of this genus are, in fact, garden-worthy plants.
That said, a number of members of the Polygonum genus are also weeds.
Although it's a weed, that smartweed I saw gracing the manure pile is easy to root out. Unless you neglect weeding unduly long, allowing the plant to root at its knees, a single yank quickly removes an abundance of greenery.
Not nearly as easy to shoo away are two smartweeds recently trying to take up residence in my garden. The first newcomer is Virginia smartweed, with relatively large leaves and a flower spike that rises to a couple of feet high. That flower spike is mostly stem, with tiny white flowers spaced widely apart. Virginia smartweed is not pretty, and is more reluctant to leave my garden than smartweed. The roots balk when yanked, so the stem breaks, leaving a significant part of the plant still in the ground and growing.
The other newcomer is wild buckwheat, a delicate, ugly vine with nothing particularly distinctive about it except that the ripe seeds resemble buckwheat grains. (Buckwheat is a relative of smartweeds.) Unfortunately, being innocuous is what allows wild buckwheat to insinuate itself into my garden, twining its fine stems around the coneflowers, monkshoods and honeysuckle vines. Once found, wild buckwheat is, at least, easy to yank out.
"Mile-a-minute" is a name given to two smartweeds that are among the worst weeds anywhere. The first is a vining plant with prickles on its stems and leaves. With those prickles and its vining habit, it easily leaps up on shrubs, small trees and structures. The other "mile-a-minute" is sometimes called Japanese or Mexican bamboo because of the resemblance of its thick, hollow, jointed stems to true bamboo. This perennial weed is attractive, with large, heart-shaped leaves, and frothing masses of tiny, creamy-white blossoms appearing in August. Still, it's a frighteningly aggressive plant.
Yet another smartweed frightened me a few weeks ago when I visited a public garden and saw what looked like that first smartweed that caught my eye near the manure pile, except this other plant looked like smartweed on steroids. Rather than billowing on the ground below knee level, it was 6 feet high.
I was set at ease when I learned that the plant's name is heart's-ease, that it is a cultivated smartweed, and that it was once a popular garden plant. It's also been called "kiss me under the garden gate."
Heart's-ease is an annual that is reputedly easy to grow, readily self-seeding once it's established. Uh-oh.
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