The National Union Catalog has many uses, but this holiday season it’s become a “book tree,” a pyramid of green bound volumes adorned with a star on top.

The catalog is a compendium of publications held in more than 1,100 libraries around the country, including the Library of Congress. In the Cushing/Whitney Medical Library the volumes sit on shelves in the information room, and this year Katie Hart, a senior administrative assistant, and Melissa Funaro, an acquisitions assistant, decided to put them to good use. They’d heard about a book tree at another medical library and on Monday, Dec. 9, they did the same. It is the first such tree to adorn the Medical Historical Library.

Assembly took about four hours and required about 300 volumes of the “enormous, hefty book.” The hard part, they said, was making the base layer. “It was a conundrum for a while, trying to figure out how big,” Funaro said.

“We went back and forth and we tried a few different sizes until we found one that worked. It was 7 feet in diameter and that equaled out to about 14 or 15 books,” Hart said.

From its 7-foot-wide base the tree tapers to a height of about 6 feet with a star that adds a few more inches. On Friday, Dec. 13, they added a string of lights and other decorations.

Asked if it’s a holiday tree or a Christmas tree, Hart said, “It’s a book tree. With a star on top.”