Although a parasitic plant with poisonous berries, mistletoe has been known for generations a having life-giving powers.

“The practice of kissing under mistletoe came from ancient Celtic mythology,” said Ann Weber of Smithfield Gardens. “In later years, you had to remove a berry every time you kissed someone under the mistletoe. When the berries were gone, there was no more kissing under that piece.”

Mistletoe grows on trees from New Jersey to Florida with some rarer species in the West. It favors oak and hickories.

As a parasitic plant, it has no roots of its own, but rather has “sinkers” that penetrate into its host’s tissues. It would take several mistletoe plants to kill a host plant, and it would take years for the decline to complete. Once the host plant died, the mistletoe would die, as well.

The ancient Greeks believed mistletoe bestowed fertility and possessed life-giving powers.

One Nordic folk legend pieced together from Internet accounts holds that the goddess Frigga had a son, Balder, god of summer’s sun, who had a dream that he would die. The goddess became so alarmed that she went to air, fire, water, earth and every plant and animal seeking a promise that they would not hurt Balder.

She forgot one plant: mistletoe. Loki, god of evil, made an arrow of mistletoe and gave it to the god of winter, who shot Balder dead. After three days of darkness, Frigga restored her son to life. It was fabled the tears she shed for her son turned to white pearls on the mistletoe.

She was so overjoyed at her son’s revival, it was said she kissed everyone who passed beneath the tree. From then on, whoever stood beneath the plant would not be harmed, but only receive a kiss.

Later, Scandinavians believed mistletoe was a peace-bringing plant under which leaders would make truces and warring spouses would “kiss and make up.”

By the 18th century, it was believed if a girl was caught standing under mistletoe, or kissing ball, she could not refuse a kiss. If the girl remained unkissed, she could not expect to marry the following year.

It is now a popular seasonal decoration.

“About Christmastime, it’s cold and leaves are falling off trees. If you want evergreen decorations, it’s more novel than a needled evergreen, and the berries aren’t red like holly. It’s something a little bit different,” Weber said.