Carnivorous plants are rare, but like the man who bit the dog, they get a lot of attention. Less spectacular but much more common than carnivores like the famous Venus fly trap is dodder, a plant that preys not on animals but on other plants. Some 145 species of this vine, including a couple of dozen in Texas, twine their way around the tropical and temperate regions of the world; all are classified in the single genus Cuscuta, though in most cases a non-specialist would be hard-pressed to tell one local species from another. Botanists once placed the genus in the Convolvulaceae, the morning-glory family, many of whose members are also vines. Then botanists created the family Cuscutaceae, with Cuscuta as its sole genus. Now they’ve moved Cuscuta back into the Convolvulaceae. Oh, those confounding, convolving botanists.
Like most plants, dodder begins its life on the ground, where a seed sprouts and puts down roots. Soon the new plant sends out tendrils in search of a suitable host, and when a tendril finds a victim, it attaches to it with tiny suckers that allow the dodder to puncture its unwilling host and extract nutrients. Once dodder makes that necessary contact, its roots, simple from the start, wither away, and the plant lives from then on in the “canopy” above the ground, even though that canopy is often only a few inches from the earth that the dodder has left behind. Where other plants have intricate roots, dodder’s intricacy resides in its above-ground strands, which turn into a crazy cat’s cradle that can repeatedly bridge the gap between one neighboring victim and the next. As dodder grows, it mostly loses whatever chlorophyll it might originally have had but no longer needs; its useless leaves, vestigial from the start, never become more than minute, functionless scales.
For a plant so small, dodder produces surprisingly many flowers, each measuring only about an eighth of an inch across. In fact the flowers are so tiny, and the plant generally so close to the ground, that a person walking by may not even notice that those flowers exist. But anyone who bends down and uses a magnifying glass or a close-up lens to see the waxy, fleshy, five-lobed flowers will likely find them unexpectedly pretty. Perhaps because the flowers are inconspicuous and the plant’s eating habits unsavory, no one has ever taken to calling the blossoms Texas stars, which would otherwise be an appropriate name.
Just as some animals specialize in the animals they prey upon, some species of dodder attack particular plants or groups of plants, while other dodder species, having caught the meme of diversity long before there was such a meme, became more egalitarian predators. Common host plants in Texas include buttonbush, sumpweed, verbena, pigweed, and—horrors!—the state flower, the beloved bluebonnet. Farmers may or may not care about bluebonnets, which are of little commercial value, but they do get riled up when dodder attacks their crops. That hatred is hardly a new thing. Accounts come down to us from ancient times of methods that could supposedly work wonders in ridding dodder from a field. “Wonders” is the operational word here, because many of the methods involved “natural magic” rather than a scientific approach to nature.
In 1933 H.J. Rose wrote about the Geoponica, a 10th century Byzantine collection of advice on farming and other country pursuits. Because dodder was known in Medieval Greek as lion’s grass, presumably due to a lion’s fierce method of attacking its prey, people back then believed that anything that would repel a lion would repel the similarly named dodder. One bit of ancient folklore held that lions are afraid of roosters, so the Geoponica claimed that sprinkling the blood of a rooster at the four corners of a field would keep lion’s grass from growing there. But why sacrifice a farm animal when there was another method that would let the rooster live and would also provide unaccustomed entertainment for the farmer? Here’s that other approach: A marriageable girl must strip completely naked and let down her hair; she must then take a [rooster] in her hands and circumambulate the place; the weed will at once disappear.
I’ve pored over the advice that today’s agricultural extension agents have given for dealing with dodder and have been surprised that not one of them has recommended that tried-and-true method.
In another connection to the Middle East, the Illustrated Flora of North Central Texas explains that the genus Cuscuta takes its name from the Arabic word kushkut or kusat, meaning a tangled wisp of hair. That makes sense, given dodder’s common appearance as a mass of tangled yellow or orange threads. Less certain is the origin of the English word dodder, which the Oxford English Dictionary says may come from a Middle Dutch word meaning the yellow of an egg, perhaps as a metaphor for the color of dodder’s strands or flowers. The colors match, but nothing else about a yolk seems appropriate to describe dodder’s appearance or behavior. We are back on solid ground, though, when we reject any connection to the English verb dodder, which means tremble or shake, because this parasitic plant does neither, or at least no more than any other plant when caught in a gust of wind.
English speakers have given dodder some colorful colloquial names. Positive ones, based on the yellow to orange color of its many fine strands, are gold thread and angel hair. In our secular culture that last probably calls to mind only angel hair pasta, which is as good an image as any for the way a first-time observer of dodder see its filaments. In contrast, the 1847 book Thoughts Among Flowers called on dodder as a religious metaphor for the way sinners should cling to Christ for sustenance:
Dodder is a very singular plant, almost destitute of leaves, parasitical and creeping. It decays at the root, and fastens itself upon hops, flax, nettles, and beans, from which it draws its nourishment, and eventually strangles its benefactor. It is impossible for the most active mind to invent anything more strikingly illustrative of the case in which the sinner stands before God, than this remarkable fact in the history of plants supplies. As is the dodder, such is he… who… desires nothing more earnestly, than that we should cling to him, be lost in him, and draw from him the life that has no end.
Negative names for dodder take us out of the angelic realm and into the diabolical: witches’ shoelaces, devil’s-thread, and devil’s-gut. Dodder’s twining appearance and parasitic nature are reflected in the vernacular names strangle-weed, strangle-vine, tangle-gut, and even scald, perhaps by analogy with the way that misdirected hot liquid or steam can damage the skin of those other rootless creatures better known as human beings.
Yet another name, love vine, is open to interpretation. We sing the praises of love, but if dodder loves its host, it does so with a clinging, smothering, debilitating sort of love. Even so, some cultures have used that very property as a test for the faithfulness of love. In around 1912 Melvin Randolph Gilmore provided this account of a tradition from the Missouri River region:
The dodder vine was used by Pawnee maidens to divine whether their suitors were sincere. A girl having plucked a vine, with the thought of the young man in mind tossed the vine over her shoulder, into the weeds of host species of this dodder. Then, turning round, she marked the plant on which the vine fell. The second day after she would return to see whether the dodder had attached itself and was growing on the host. If so, she went away content with full assurance of her lover’s sincerity and faithfulness. If the dodder had not twined and attached itself, she took it as a warning not to trust him.
Ellen D. Schulz provided a similar account in her classic 1928 Texas Wild Flowers; she wrote that dodder has long played a part in the romantic traditions of the Old South by offering an alternative to the common but simplistic (s)he-loves-me-(s)he-loves-me-not plucking of the “petals” of a daisy. In the Southern variation, you swing a piece of dodder around your head three times and throw it over your shoulder, then walk away without looking back to see where the dodder has landed. After three days you return to the spot and check whether the dodder has attached itself to a plant: if so, then your sweetheart loves you. Unlike the 50-50 odds of pulling petals out of a flower, this method supposedly has a higher success rate due to dodder’s skill in latching on to nearby prey. Thus is sound botanical knowledge transmuted into folklore, all in the service of that tangle of emotions we call love.