NEW YORK — A certain plant of the pea family has been appreciated in Japan — poetically, dietarily and medicinally — since ancient times. So, in the oldest extant anthology of Japanese poetry, the "Man'yoshu," it is used as an epithet for "without interruption," "for a long time" and so forth, because its most impressive attribute is "vitality," as a photo-packed Japanese Web site for "seasonal flowers" (kisetsu no hana) puts it. Its vines grow not just fast but also unendingly.

For example, in the early eighth century, when Prince Yamasaki wrote an elegy upon Prince Ishida's death, he referred to the plant to lament, "I had expected to come to visit you forever and ever."

Similarly, Lady Sakanoue cited the plant in replying to a man who had sent her a poem saying days had passed without his seeing her. In her poem, she noted she had wondered if something had happened to him because his messenger who used to come "without interruption" had "faltered."