Bill Kuhl, proprietor of McLean Nurseries in Baltimore says business booms during the holidays with customers looking for decorative holly. (Lloyd Fox/Baltimore Sun)

It has, to paraphrase an old English carol, prickles as sharp as thorns, bark as bitter as gall and berries as bright as life-giving blood.

Friends and loved ones gathering on Christmas will see it in wreaths and on mantels, its image on cards, on stockings and on presents under the tree.

And as it has done every winter since long before the Roman Conquest, the plant genus known as Ilex, or holly, will be working its green-and-red magic, evoking feelings linked to the Christian tradition and spreading general holiday cheer.

"There's something magical about holly, especially this time of year," says William N. (Bill) Kuhl, an expert on the species who has done his part to preserve this Yuletide tradition for the past 40 years.

Kuhl owns McLean Nurseries, a nine-acre farm on a Parkville hillside known as one of the premier breeding grounds for the plant in the United States. Founded in 1946, the place features hundreds of holly trees, many of them 70 or 80 years old, in more than 100 varieties.

"Bill is one of the most knowledgeable people on this subject you're ever going to meet, and it's largely thanks to his efforts that [McLean Nurseries] holds a special place in the hearts of holly enthusiasts," says Carmen Gianforte, a life member and trustee of the Holly Society of America, which has promoted the species for 65 years.

Kuhl, 69, has his hands full year round with the full complement of the hollyman's labors — keeping the crops bountiful, propagating new varieties, staying abreast of news and selling specimens of all shapes and sizes. But this time of year is the most intense.

Between Thanksgiving and Christmas, he and his team of four dedicated ladies create as many as 500 wreaths along with other holly arrangements, nearly all of them from materials found on the farm.

The season accounts for between 30 and 40 percent of the nursery's annual income, but that's only part of what motivates the self-described "elves" as Santa's approach draws near.

"It's such a joy to see people's faces when they see the finished product," says Miriam Miceli, who has woven wreaths on her specialized easel for 25 winters. "Some of our customers have been coming here for 40 or 50 years. But the freshness always seems to surprise them."

One morning last week, as the team assembled in the cluttered shed they call an office. Miceli threaded red and yellow holly berries into a 42-inch base for a local church. Fellow "elf" Mary Oros crafted arrangements in a basket.

It was a perfect chance for their boss, a portly, bandy-legged gentleman who might make a good Santa, given a beard, to discuss his favorite subject.

To those who love it, like the hundreds of gardeners, growers, retailers and botanists who belong to the holly society, ilex is endlessly fascinating.

It's attractive in unique ways, Kuhl says, blending the dark and the bright, the harsh and the inviting. It comes in thousands of varieties, many of them adaptable and hardy. They make excellent understory in forests, the berries good food for robins, mockingbirds and bluebirds.

Most hollies, he says, can thrive amidst a city's salt and exhaust — holly lines a lot of noise walls, including many along Interstate 695 — and some are thick enough to make great screens or wind breaks.

And "holly nuts," as he calls enthusiasts, introduce new forms, favoring desired sizes, leaf shapes, berry colors and growing tendencies.

They can do so via male-female pollination or through asexual reproduction, which Kuhl proceeds to illustrate.

Seated at a work table, he flicks the bark off a holly stem with a knife, exposing the live tissue beneath.

Take such a clipping from any specimen, he says, then set it in rooting hormone, anchor it in peat moss and perlite (a planting medium) and mist and protect it for several months. Then it will become a sprig, then a new version of the original tree.