Dear Alice,

I’ve got a question that comes to me only while riding chair lifts at Japanese ski resorts, not the most opportune time or place to send an e-mail. But yesterday, while cleaning last year’s debris out of my ski jacket, I discovered a trail map with a scribbled reminder to ask you this: What the heck are those nest-like balls you see up in trees in winter? I’ve spotted them along ski slopes in Nagano, Akita and Iwate Prefectures. At first I thought they were nests of leaves made by squirrels or some other small animals, but they don’t seem dense enough to provide shelter.

Lars C., Saitama

Dear Lars,

Ho, ho, ho! Your question is timelier than you may know. Those balls are mistletoe, a plant that settles in the branches of trees and grows into orbs as big as one meter in diameter. They’re up there year-round but become most noticeable in winter when the host tree has dropped its leaves. Mistletoe is what’s called a semi-parasitic plant (han-kisei shokubutsu), which means it depends on its host for water and minerals, but produces its own carbohydrates in its leaves through photosynthesis.

In Japanese, mistletoe is called yadorigi, which comes from the verb yadoru, meaning to lodge or dwell. This leafy lodger’s booking agents are birds, who sometimes stop in trees after mistletoe-berry meals and wipe the sticky seeds off their beaks onto branches. The birds also do a lot of package deals: flyby deposits of the seeds in their droppings.

Thanks to their efforts, mistletoe grows all over Japan, except in Okinawa and the islands off Kagoshima Prefecture, according to Tatsundo Fukuhara, a botanist at Fukuoka University of Education. There are several different species of mistletoe in Japan, some of which settle in deciduous trees (rakuyoju) such as oaks, elms and cherries. Based on where you were skiing, Fukuhara guesses you saw Viscum album var. coloratum — mistletoe with yellowish green or red berries.

Japanese people have obviously known this plant for a very long time because it makes an appearance in the “Man’yoshu,” a collection of Japanese poems from the seventh and eighth centuries. “Yadorigi” is also the title of a chapter in “Tale of Genji,” the 11th-century classic of Japanese literature. And this is where my research hit a snag: although my plant-name dictionary states unequivocally that yadorigi is mistletoe, two of the three great English translators of “Tale of Genji” seemed to think differently. Arthur Waley translated that chapter as “The Mistletoe,” but Edward Seidensticker and Royall Tyler opted for “The Ivy.”

I knew I’d have a hard time convincing anyone that yadorigi is mistletoe if the late Seidensticker says it’s ivy, so I went to the library and lined up copies of all three translations as well as the Japanese original. It turns out that while the chapter is entitled “Yadorigi” (or “Yadoriki”), the plant in the story itself is something called kodani.

This is apparently one of many plant names lost over the centuries, because nobody today seems to know exactly what it is or was. In footnotes, each of the translators acknowledged this and explained why they used the English they did. Tyler helpfully notes that the chapter derives its title from a poetic exchange between two characters in which both of their poems play on the two meanings of the syllables of yadoriki, which he says are “climbing vine” and “I lodged [here].”

As in Europe, where people ascribed healing and mystical properties to mistletoe long before it became associated with Christmas decorations, Japanese people once believed this plant held special powers. Putting a sprig of yadorigi in your hair was supposed to bring happiness, and the leaves and stems of the plant were (and still are) used in preparing various medicines.

Modern scientists have determined that the mistletoe plant contains chemicals such as oleanolic acid, avicularin, inositol, quercetin and lupeol, all of which are being investigated as possible cancer-fighting agents.

Probably the most surprising thing I came across in researching your question was a reference to yadorigi in a document about kyuko shokubutsu, a term unfamiliar to most Japanese today, that refers to plants that can serve as a source of emergency food in case of famine.

Hunger used to be a serious problem in Japan, and enlightened leaders such as Uesugi Harunori (1751-1822), the ninth daimyo to head the Yonezawa domain, actively promoted knowledge about edible wild plants as a measure to prevent starvation during famine.

There is now a small resurgence of interest in the subject as some people, concerned about Japan’s heavy dependence on food imports, ponder what we’ll all eat if war or natural disaster interrupts supplies of food from overseas.

I once spent an interesting morning hunting sansai (mountain vegetables, or the more common sorts of edible wild plants), and am thoroughly convinced that I’d starve if I had to rely on my own powers of plant identification. But those balls of mistletoe are unmistakable! I checked and am happy to report that the leaves and stems of yadorigi are entirely edible. That’s something to remember should we get stranded while skiing, or heaven forbid, there’s ever another famine in Japan.

Please enjoy the upcoming holidays. I hope you’ll keep reading next year!

Puzzled by something you’ve seen? Send a description, or better yet a photo, with the address where you saw it to: whattheheckjt@yahoo.co.jp or A&E Dept., The Japan Times, 5-4, Shibaura 4-chome, Minato-ku, Tokyo 108-8071.